21451531131 has 32 divisors (see below), whose sum is σ = 32550693120. Its totient is φ = 13954876992.

The previous prime is 21451531121. The next prime is 21451531139. The reversal of 21451531131 is 13113515412.

21451531131 is a `hidden beast` number, since 2 + 14 + 515 + 3 + 1 + 131 = 666.

It is not a de Polignac number, because 21451531131 - 2⁹ = 21451530619 is a prime.

It is a super-2 number, since 2×21451531131² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 21451531095 and 21451531104.

It is not an unprimeable number, because it can be changed into a prime (21451531139) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1265196 + ... + 1282038.

It is an arithmetic number, because the mean of its divisors is an integer number (1017209160).

Almost surely, 2^21451531131 is an apocalyptic number.

21451531131 is a deficient number, since it is larger than the sum of its proper divisors (11099161989).

21451531131 is a wasteful number, since it uses less digits than its factorization.

21451531131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17992 (or 17986 counting only the distinct ones).

The product of its digits is 1800, while the sum is 27.

The spelling of 21451531131 in words is "twenty-one billion, four hundred fifty-one million, five hundred thirty-one thousand, one hundred thirty-one".