21515005252 has 24 divisors (see below), whose sum is σ = 40724595800. Its totient is φ = 9886634496.

The previous prime is 21515005241. The next prime is 21515005271. The reversal of 21515005252 is 25250051512.

It can be written as a sum of positive squares in 4 ways, for example, as 4962638916 + 16552366336 = 70446^2 + 128656^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21515005252.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 891477 + ... + 915292.

Almost surely, 2^21515005252 is an apocalyptic number.

It is an amenable number.

21515005252 is a deficient number, since it is larger than the sum of its proper divisors (19209590548).

21515005252 is a wasteful number, since it uses less digits than its factorization.

21515005252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1807015 (or 1807013 counting only the distinct ones).

The product of its (nonzero) digits is 5000, while the sum is 28.

Adding to 21515005252 its reverse (25250051512), we get a palindrome (46765056764).

The spelling of 21515005252 in words is "twenty-one billion, five hundred fifteen million, five thousand, two hundred fifty-two".