643425931 has 2 divisors, whose sum is σ = 643425932. Its totient is φ = 643425930.

The previous prime is 643425919. The next prime is 643425941. The reversal of 643425931 is 139524346.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 643425931 - 2¹³ = 643417739 is a prime.

It is a super-2 number, since 2×643425931² = 827993857366433522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (643425901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321712965 + 321712966.

It is an arithmetic number, because the mean of its divisors is an integer number (321712966).

Almost surely, 2^643425931 is an apocalyptic number.

643425931 is a deficient number, since it is larger than the sum of its proper divisors (1).

643425931 is an equidigital number, since it uses as much as digits as its factorization.

643425931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 77760, while the sum is 37.

The square root of 643425931 is about 25365.8418153232. The cubic root of 643425931 is about 863.3088371610.

The spelling of 643425931 in words is "six hundred forty-three million, four hundred twenty-five thousand, nine hundred thirty-one".