21040502531 has 4 divisors (see below), whose sum is σ = 21385428864. Its totient is φ = 20695576200.

The previous prime is 21040502521. The next prime is 21040502543. The reversal of 21040502531 is 13520504012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21040502531 - 2³⁴ = 3860633347 is a prime.

It is a super-2 number, since 2×21040502531² (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 = 21040502497 and 21040502506.

It is not an unprimeable number, because it can be changed into a prime (21040502521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 172463075 + ... + 172463196.

It is an arithmetic number, because the mean of its divisors is an integer number (5346357216).

Almost surely, 2^21040502531 is an apocalyptic number.

21040502531 is a deficient number, since it is larger than the sum of its proper divisors (344926333).

21040502531 is an equidigital number, since it uses as much as digits as its factorization.

21040502531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 344926332.

The product of its (nonzero) digits is 1200, while the sum is 23.

The spelling of 21040502531 in words is "twenty-one billion, forty million, five hundred two thousand, five hundred thirty-one".