661260641625 has 40 divisors (see below), whose sum is σ = 1232785783944. Its totient is φ = 352672336800.

The previous prime is 661260641599. The next prime is 661260641683. The reversal of 661260641625 is 526146062166.

661260641625 is a `hidden beast` number, since 6 + 6 + 1 + 2 + 606 + 4 + 16 + 25 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 118991882304 + 542268759321 = 344952^2 + 736389^2 .

It is not a de Polignac number, because 661260641625 - 2¹⁵ = 661260608857 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 32644722 + ... + 32664971.

Almost surely, 2^661260641625 is an apocalyptic number.

It is an amenable number.

661260641625 is a deficient number, since it is larger than the sum of its proper divisors (571525142319).

661260641625 is an equidigital number, since it uses as much as digits as its factorization.

661260641625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65309720 (or 65309701 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 45.

The spelling of 661260641625 in words is "six hundred sixty-one billion, two hundred sixty million, six hundred forty-one thousand, six hundred twenty-five".