645877665947 has 2 divisors, whose sum is σ = 645877665948. Its totient is φ = 645877665946.

The previous prime is 645877665931. The next prime is 645877665967. The reversal of 645877665947 is 749566778546.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 645877665947 - 2⁴ = 645877665931 is a prime.

It is not a weakly prime, because it can be changed into another prime (645877665967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322938832973 + 322938832974.

It is an arithmetic number, because the mean of its divisors is an integer number (322938832974).

Almost surely, 2^645877665947 is an apocalyptic number.

645877665947 is a deficient number, since it is larger than the sum of its proper divisors (1).

645877665947 is an equidigital number, since it uses as much as digits as its factorization.

645877665947 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2133734400, while the sum is 74.

The spelling of 645877665947 in words is "six hundred forty-five billion, eight hundred seventy-seven million, six hundred sixty-five thousand, nine hundred forty-seven".