The OpenPGP message you posted is a _signature_, not a key. As it was issued by GnuPG, I assume you're using GnuPG anyway. To export your public key, run `gpg --armor --export [key-id]`. `--armor` wraps the output in a base64-like encoding (like the signature block you provided in your question), otherwise you'll get binary output. If you don't know your key-id, you can look it up through `gpg --list-keys`, possibly followed by a search pattern on a user ID you added -- for example your mail address.

The public key also contains user IDs, certifications, subkeys, ... and can be rather lengthy. The beginning of my own public key export:

    -----BEGIN PGP PUBLIC KEY BLOCK-----
    Version: GnuPG v1
    
    mQQNBFDaK/sBIADm2gjnw7aPoNIoCy7gj85btwZU+zGkvtGonznlLrXELdU6zR3u
    VHNCn9vAl6OoU32r+suFvGdX+7MjiPbGKwJFOvICpAVh6bV55+hdqJbS02cpPmJH
    1BrrUAmm6ZVEybGd+II1pTI6Mt/SAI1E/59VIBdC/1AwsxQtCTFeyaLqTdyd1FhQ
    chkjcvdRHLb4cEqldAGqBL7SbiSNOP3p+vX8iwRN6PQ/erAGseawHnunuNIna+tA
    t4te/MkI2uxT0KjsfF/NWHCB2aXt++egP8jGSaHRsVOlfHRVA3hHcUDlnW9DZRvG
    QabHFcZvfcXAlNIRYKUzDIHEwpavAmHeGNhc2GNmDcDRF56741grVLNQT58vxK5o
    dBLlC8ANckvE5ymdIKVPm+t5q10kFOAATcnmDV0oBt+15vzI3f+88yCoY904UWdY
    [...]

If you want to dump the RSA primes, use the `pgpdump` tool (not included with GnuPG and has to be installed separately, but should be available readily packaged for all relevant distributions). To print the primes, you can directly pipe GnuPG's `--export` output into `pgpdump (consider storing the output to a file or piping into `less`, as the output can get really long):

    gpg --export[key-id] | pgpdump -i

To understand the output of `pgpdump` (and the structure of OpenPGP messages), read [RFC 4880](https://tools.ietf.org/html/rfc4880).