1221025100 has 36 divisors (see below), whose sum is σ = 2714258568. Its totient is φ = 476496000.

The previous prime is 1221025031. The next prime is 1221025111. The reversal of 1221025100 is 15201221.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 144806 + ... + 153005.

Almost surely, 2^1221025100 is an apocalyptic number.

1221025100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221025100 is an abundant number, since it is smaller than the sum of its proper divisors (1493233468).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221025100 is a wasteful number, since it uses less digits than its factorization.

1221025100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 297866 (or 297859 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 1221025100 is about 34943.1695757554. The cubic root of 1221025100 is about 1068.8289222750.

Adding to 1221025100 its reverse (15201221), we get a palindrome (1236226321).

The spelling of 1221025100 in words is "one billion, two hundred twenty-one million, twenty-five thousand, one hundred".