21815800252 has 24 divisors (see below), whose sum is σ = 39578378112. Its totient is φ = 10510713600.

The previous prime is 21815800243. The next prime is 21815800297. The reversal of 21815800252 is 25200851812.

It is a happy number.

It is a congruent number.

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, 348649 + ... + 406432.

It is an arithmetic number, because the mean of its divisors is an integer number (1649099088).

Almost surely, 2^21815800252 is an apocalyptic number.

It is an amenable number.

21815800252 is a deficient number, since it is larger than the sum of its proper divisors (17762577860).

21815800252 is a wasteful number, since it uses less digits than its factorization.

21815800252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 755349 (or 755347 counting only the distinct ones).

The product of its (nonzero) digits is 12800, while the sum is 34.

The spelling of 21815800252 in words is "twenty-one billion, eight hundred fifteen million, eight hundred thousand, two hundred fifty-two".