645554971 has 2 divisors, whose sum is σ = 645554972. Its totient is φ = 645554970.

The previous prime is 645554941. The next prime is 645554977. The reversal of 645554971 is 179455546.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 645554971 - 2⁵ = 645554939 is a prime.

It is not a weakly prime, because it can be changed into another prime (645554977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322777485 + 322777486.

It is an arithmetic number, because the mean of its divisors is an integer number (322777486).

Almost surely, 2^645554971 is an apocalyptic number.

645554971 is a deficient number, since it is larger than the sum of its proper divisors (1).

645554971 is an equidigital number, since it uses as much as digits as its factorization.

645554971 is an evil number, because the sum of its binary digits is even.

The product of its digits is 756000, while the sum is 46.

The square root of 645554971 is about 25407.7738300702. The cubic root of 645554971 is about 864.2599932540.

The spelling of 645554971 in words is "six hundred forty-five million, five hundred fifty-four thousand, nine hundred seventy-one".