21402530531 has 2 divisors, whose sum is σ = 21402530532. Its totient is φ = 21402530530.

The previous prime is 21402530507. The next prime is 21402530533. The reversal of 21402530531 is 13503520412.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21402530531 - 2³⁴ = 4222661347 is a prime.

It is a super-2 number, since 2×21402530531² (a number of 21 digits) contains 22 as substring.

Together with 21402530533, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21402530531.

It is not a weakly prime, because it can be changed into another prime (21402530533) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10701265265 + 10701265266.

It is an arithmetic number, because the mean of its divisors is an integer number (10701265266).

Almost surely, 2^21402530531 is an apocalyptic number.

21402530531 is a deficient number, since it is larger than the sum of its proper divisors (1).

21402530531 is an equidigital number, since it uses as much as digits as its factorization.

21402530531 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3600, while the sum is 26.

The spelling of 21402530531 in words is "twenty-one billion, four hundred two million, five hundred thirty thousand, five hundred thirty-one".