645442657 has 2 divisors, whose sum is σ = 645442658. Its totient is φ = 645442656.

The previous prime is 645442649. The next prime is 645442663. The reversal of 645442657 is 756244546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 619064161 + 26378496 = 24881^2 + 5136^2 .

It is a cyclic number.

It is not a de Polignac number, because 645442657 - 2³ = 645442649 is a prime.

It is not a weakly prime, because it can be changed into another prime (645442627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322721328 + 322721329.

It is an arithmetic number, because the mean of its divisors is an integer number (322721329).

Almost surely, 2^645442657 is an apocalyptic number.

It is an amenable number.

645442657 is a deficient number, since it is larger than the sum of its proper divisors (1).

645442657 is an equidigital number, since it uses as much as digits as its factorization.

645442657 is an evil number, because the sum of its binary digits is even.

The product of its digits is 806400, while the sum is 43.

The square root of 645442657 is about 25405.5635048703. The cubic root of 645442657 is about 864.2098688746.

The spelling of 645442657 in words is "six hundred forty-five million, four hundred forty-two thousand, six hundred fifty-seven".