21011255252 has 24 divisors (see below), whose sum is σ = 39805473792. Its totient is φ = 9646725600.

The previous prime is 21011255173. The next prime is 21011255257. The reversal of 21011255252 is 25255211012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011255257) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 1047824 + ... + 1067687.

It is an arithmetic number, because the mean of its divisors is an integer number (1658561408).

Almost surely, 2^21011255252 is an apocalyptic number.

It is an amenable number.

21011255252 is a deficient number, since it is larger than the sum of its proper divisors (18794218540).

21011255252 is a wasteful number, since it uses less digits than its factorization.

21011255252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2115719 (or 2115717 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 26.

Adding to 21011255252 its reverse (25255211012), we get a palindrome (46266466264).

The spelling of 21011255252 in words is "twenty-one billion, eleven million, two hundred fifty-five thousand, two hundred fifty-two".