21275508731 has 2 divisors, whose sum is σ = 21275508732. Its totient is φ = 21275508730.

The previous prime is 21275508689. The next prime is 21275508767. The reversal of 21275508731 is 13780557212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21275508731 - 2³⁴ = 4095639547 is a prime.

It is a super-2 number, since 2×21275508731² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21275505731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10637754365 + 10637754366.

It is an arithmetic number, because the mean of its divisors is an integer number (10637754366).

Almost surely, 2^21275508731 is an apocalyptic number.

21275508731 is a deficient number, since it is larger than the sum of its proper divisors (1).

21275508731 is an equidigital number, since it uses as much as digits as its factorization.

21275508731 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 117600, while the sum is 41.

The spelling of 21275508731 in words is "twenty-one billion, two hundred seventy-five million, five hundred eight thousand, seven hundred thirty-one".