21515451430531 has 2 divisors, whose sum is σ = 21515451430532. Its totient is φ = 21515451430530.

The previous prime is 21515451430519. The next prime is 21515451430579. The reversal of 21515451430531 is 13503415451512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21515451430531 - 2¹¹ = 21515451428483 is a prime.

It is a super-2 number, since 2×21515451430531² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21515451430511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10757725715265 + 10757725715266.

It is an arithmetic number, because the mean of its divisors is an integer number (10757725715266).

Almost surely, 2^{21515451430531} is an apocalyptic number.

21515451430531 is a deficient number, since it is larger than the sum of its proper divisors (1).

21515451430531 is an equidigital number, since it uses as much as digits as its factorization.

21515451430531 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 180000, while the sum is 40.

The spelling of 21515451430531 in words is "twenty-one trillion, five hundred fifteen billion, four hundred fifty-one million, four hundred thirty thousand, five hundred thirty-one".