21747311731 has 2 divisors, whose sum is σ = 21747311732. Its totient is φ = 21747311730.

The previous prime is 21747311711. The next prime is 21747311737. The reversal of 21747311731 is 13711374712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21747311731 - 2¹⁷ = 21747180659 is a prime.

It is a super-2 number, since 2×21747311731² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21747311737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10873655865 + 10873655866.

It is an arithmetic number, because the mean of its divisors is an integer number (10873655866).

Almost surely, 2^21747311731 is an apocalyptic number.

21747311731 is a deficient number, since it is larger than the sum of its proper divisors (1).

21747311731 is an equidigital number, since it uses as much as digits as its factorization.

21747311731 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24696, while the sum is 37.

The spelling of 21747311731 in words is "twenty-one billion, seven hundred forty-seven million, three hundred eleven thousand, seven hundred thirty-one".