21531254120 has 64 divisors (see below), whose sum is σ = 52488025920. Its totient is φ = 7917364224.

The previous prime is 21531254117. The next prime is 21531254161. The reversal of 21531254120 is 2145213512.

It is a self number, because there is not a number n which added to its sum of digits gives 21531254120.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 338942 + ... + 397421.

It is an arithmetic number, because the mean of its divisors is an integer number (820125405).

Almost surely, 2^21531254120 is an apocalyptic number.

21531254120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21531254120 is an abundant number, since it is smaller than the sum of its proper divisors (30956771800).

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

21531254120 is a wasteful number, since it uses less digits than its factorization.

21531254120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 736434 (or 736430 counting only the distinct ones).

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

Adding to 21531254120 its reverse (2145213512), we get a palindrome (23676467632).

The spelling of 21531254120 in words is "twenty-one billion, five hundred thirty-one million, two hundred fifty-four thousand, one hundred twenty".