21015251000 has 64 divisors (see below), whose sum is σ = 50222090880. Its totient is φ = 8227228800.

The previous prime is 21015250999. The next prime is 21015251027. The reversal of 21015251000 is 15251012.

It is a self number, because there is not a number n which added to its sum of digits gives 21015251000.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 176567 + ... + 270566.

It is an arithmetic number, because the mean of its divisors is an integer number (784720170).

Almost surely, 2^21015251000 is an apocalyptic number.

21015251000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21015251000 is an abundant number, since it is smaller than the sum of its proper divisors (29206839880).

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

21015251000 is a wasteful number, since it uses less digits than its factorization.

21015251000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 447201 (or 447187 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 17.

The spelling of 21015251000 in words is "twenty-one billion, fifteen million, two hundred fifty-one thousand".