21253640431 has 16 divisors (see below), whose sum is σ = 22812832224. Its totient is φ = 19729583104.

The previous prime is 21253640351. The next prime is 21253640459. The reversal of 21253640431 is 13404635212.

It is not a de Polignac number, because 21253640431 - 2³³ = 12663705839 is a prime.

It is a super-2 number, since 2×21253640431² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21253640393 and 21253640402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253640131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 858381 + ... + 882793.

It is an arithmetic number, because the mean of its divisors is an integer number (1425802014).

Almost surely, 2^21253640431 is an apocalyptic number.

21253640431 is a deficient number, since it is larger than the sum of its proper divisors (1559191793).

21253640431 is a wasteful number, since it uses less digits than its factorization.

21253640431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25130.

The product of its (nonzero) digits is 17280, while the sum is 31.

The spelling of 21253640431 in words is "twenty-one billion, two hundred fifty-three million, six hundred forty thousand, four hundred thirty-one".