21251010012 has 48 divisors (see below), whose sum is σ = 51297641472. Its totient is φ = 6840109440.

The previous prime is 21251009999. The next prime is 21251010023. The reversal of 21251010012 is 21001015212.

It is a junction number, because it is equal to n+sod(n) for n = 21251009973 and 21251010000.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 107503 + ... + 232505.

It is an arithmetic number, because the mean of its divisors is an integer number (1068700864).

Almost surely, 2^21251010012 is an apocalyptic number.

It is an amenable number.

21251010012 is an abundant number, since it is smaller than the sum of its proper divisors (30046631460).

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

21251010012 is a wasteful number, since it uses less digits than its factorization.

21251010012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125498 (or 125496 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 15.

Adding to 21251010012 its reverse (21001015212), we get a palindrome (42252025224).

The spelling of 21251010012 in words is "twenty-one billion, two hundred fifty-one million, ten thousand, twelve".