21101215252 has 24 divisors (see below), whose sum is σ = 42106951656. Its totient is φ = 9166138368.

The previous prime is 21101215241. The next prime is 21101215271. The reversal of 21101215252 is 25251210112.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 3623317636 + 17477897616 = 60194^2 + 132204^2 .

It is a super-2 number, since 2×21101215252² (a number of 21 digits) contains 22 as substring.

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, 11934193 + ... + 11935960.

It is an arithmetic number, because the mean of its divisors is an integer number (1754456319).

Almost surely, 2^21101215252 is an apocalyptic number.

It is an amenable number.

21101215252 is a deficient number, since it is larger than the sum of its proper divisors (21005736404).

21101215252 is a wasteful number, since it uses less digits than its factorization.

21101215252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23870187 (or 23870185 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 22.

Adding to 21101215252 its reverse (25251210112), we get a palindrome (46352425364).

The spelling of 21101215252 in words is "twenty-one billion, one hundred one million, two hundred fifteen thousand, two hundred fifty-two".