21215251252 has 96 divisors (see below), whose sum is σ = 43892906400. Its totient is φ = 8877883392.

The previous prime is 21215251237. The next prime is 21215251259. The reversal of 21215251252 is 25215251212.

It can be written as a sum of positive squares in 16 ways, for example, as 2551866256 + 18663384996 = 50516^2 + 136614^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21215251252.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21215251259) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 18790624 + ... + 18791752.

It is an arithmetic number, because the mean of its divisors is an integer number (457217775).

Almost surely, 2^21215251252 is an apocalyptic number.

It is an amenable number.

21215251252 is an abundant number, since it is smaller than the sum of its proper divisors (22677655148).

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

21215251252 is a wasteful number, since it uses less digits than its factorization.

21215251252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1925 (or 1923 counting only the distinct ones).

The product of its digits is 4000, while the sum is 28.

The spelling of 21215251252 in words is "twenty-one billion, two hundred fifteen million, two hundred fifty-one thousand, two hundred fifty-two".