21756039427 has 2 divisors, whose sum is σ = 21756039428. Its totient is φ = 21756039426.

The previous prime is 21756039421. The next prime is 21756039497. The reversal of 21756039427 is 72493065712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21756039427 - 2²⁷ = 21621821699 is a prime.

It is not a weakly prime, because it can be changed into another prime (21756039421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10878019713 + 10878019714.

It is an arithmetic number, because the mean of its divisors is an integer number (10878019714).

Almost surely, 2^21756039427 is an apocalyptic number.

21756039427 is a deficient number, since it is larger than the sum of its proper divisors (1).

21756039427 is an equidigital number, since it uses as much as digits as its factorization.

21756039427 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 635040, while the sum is 46.

The spelling of 21756039427 in words is "twenty-one billion, seven hundred fifty-six million, thirty-nine thousand, four hundred twenty-seven".