21531164275 has 12 divisors (see below), whose sum is σ = 28269152712. Its totient is φ = 16211699840.

The previous prime is 21531164269. The next prime is 21531164279. The reversal of 21531164275 is 57246113512.

It is not a de Polignac number, because 21531164275 - 2⁷ = 21531164147 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21531164279) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 25330357 + ... + 25331206.

It is an arithmetic number, because the mean of its divisors is an integer number (2355762726).

Almost surely, 2^21531164275 is an apocalyptic number.

21531164275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21531164275 is a deficient number, since it is larger than the sum of its proper divisors (6737988437).

21531164275 is a wasteful number, since it uses less digits than its factorization.

21531164275 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50661590 (or 50661585 counting only the distinct ones).

The product of its digits is 50400, while the sum is 37.

Adding to 21531164275 its reverse (57246113512), we get a palindrome (78777277787).

The spelling of 21531164275 in words is "twenty-one billion, five hundred thirty-one million, one hundred sixty-four thousand, two hundred seventy-five".