661925691 has 12 divisors (see below), whose sum is σ = 1092702832. Its totient is φ = 378243216.

The previous prime is 661925683. The next prime is 661925707. The reversal of 661925691 is 196529166.

It is a happy number.

661925691 is a `hidden beast` number, since 6 + 619 + 25 + 6 + 9 + 1 = 666.

It is not a de Polignac number, because 661925691 - 2³ = 661925683 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661925611) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5253316 + ... + 5253441.

Almost surely, 2^661925691 is an apocalyptic number.

661925691 is a deficient number, since it is larger than the sum of its proper divisors (430777141).

661925691 is a wasteful number, since it uses less digits than its factorization.

661925691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10506770 (or 10506767 counting only the distinct ones).

The product of its digits is 174960, while the sum is 45.

The square root of 661925691 is about 25727.9165693610. The cubic root of 661925691 is about 871.5047245526.

The spelling of 661925691 in words is "six hundred sixty-one million, nine hundred twenty-five thousand, six hundred ninety-one".