21531222152 has 16 divisors (see below), whose sum is σ = 44041136400. Its totient is φ = 9786919120.

The previous prime is 21531222149. The next prime is 21531222169. The reversal of 21531222152 is 25122213512.

It is a happy number.

It is a super-2 number, since 2×21531222152² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 122336402 + ... + 122336577.

It is an arithmetic number, because the mean of its divisors is an integer number (2752571025).

Almost surely, 2^21531222152 is an apocalyptic number.

21531222152 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21531222152 is an abundant number, since it is smaller than the sum of its proper divisors (22509914248).

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

21531222152 is a wasteful number, since it uses less digits than its factorization.

21531222152 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244672996 (or 244672992 counting only the distinct ones).

The product of its digits is 2400, while the sum is 26.

Adding to 21531222152 its reverse (25122213512), we get a palindrome (46653435664).

The spelling of 21531222152 in words is "twenty-one billion, five hundred thirty-one million, two hundred twenty-two thousand, one hundred fifty-two".