645512731 has 2 divisors, whose sum is σ = 645512732. Its totient is φ = 645512730.

The previous prime is 645512719. The next prime is 645512741. The reversal of 645512731 is 137215546.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 645512731 - 2¹⁵ = 645479963 is a prime.

It is a super-2 number, since 2×645512731² = 833373371766156722, which contains 22 as substring.

It is equal to p_33572158 and since 645512731 and 33572158 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (645512701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322756365 + 322756366.

It is an arithmetic number, because the mean of its divisors is an integer number (322756366).

Almost surely, 2^645512731 is an apocalyptic number.

645512731 is a deficient number, since it is larger than the sum of its proper divisors (1).

645512731 is an equidigital number, since it uses as much as digits as its factorization.

645512731 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25200, while the sum is 34.

The square root of 645512731 is about 25406.9425748160. The cubic root of 645512731 is about 864.2411427351.

The spelling of 645512731 in words is "six hundred forty-five million, five hundred twelve thousand, seven hundred thirty-one".