661625317 has 2 divisors, whose sum is σ = 661625318. Its totient is φ = 661625316.

The previous prime is 661625311. The next prime is 661625369. The reversal of 661625317 is 713526166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 357436836 + 304188481 = 18906^2 + 17441^2 .

It is a cyclic number.

It is not a de Polignac number, because 661625317 - 2²⁷ = 527407589 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661625311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330812658 + 330812659.

It is an arithmetic number, because the mean of its divisors is an integer number (330812659).

Almost surely, 2^661625317 is an apocalyptic number.

It is an amenable number.

661625317 is a deficient number, since it is larger than the sum of its proper divisors (1).

661625317 is an equidigital number, since it uses as much as digits as its factorization.

661625317 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 45360, while the sum is 37.

The square root of 661625317 is about 25722.0783958062. The cubic root of 661625317 is about 871.3728784502.

The spelling of 661625317 in words is "six hundred sixty-one million, six hundred twenty-five thousand, three hundred seventeen".