645415036561 has 2 divisors, whose sum is σ = 645415036562. Its totient is φ = 645415036560.

The previous prime is 645415036529. The next prime is 645415036573. The reversal of 645415036561 is 165630514546.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 572679643536 + 72735393025 = 756756^2 + 269695^2 .

It is a cyclic number.

It is not a de Polignac number, because 645415036561 - 2⁵ = 645415036529 is a prime.

It is not a weakly prime, because it can be changed into another prime (645415036261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322707518280 + 322707518281.

It is an arithmetic number, because the mean of its divisors is an integer number (322707518281).

Almost surely, 2^645415036561 is an apocalyptic number.

It is an amenable number.

645415036561 is a deficient number, since it is larger than the sum of its proper divisors (1).

645415036561 is an equidigital number, since it uses as much as digits as its factorization.

645415036561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296000, while the sum is 46.

The spelling of 645415036561 in words is "six hundred forty-five billion, four hundred fifteen million, thirty-six thousand, five hundred sixty-one".