665801631 has 48 divisors (see below), whose sum is σ = 1099837440. Its totient is φ = 384183360.

The previous prime is 665801621. The next prime is 665801657. The reversal of 665801631 is 136108566.

It is a happy number.

665801631 is a `hidden beast` number, since 66 + 580 + 16 + 3 + 1 = 666.

It is not a de Polignac number, because 665801631 - 2⁵ = 665801599 is a prime.

It is a super-2 number, since 2×665801631² = 886583623684520322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665801611) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 611970 + ... + 613056.

It is an arithmetic number, because the mean of its divisors is an integer number (22913280).

Almost surely, 2^665801631 is an apocalyptic number.

665801631 is a deficient number, since it is larger than the sum of its proper divisors (434035809).

665801631 is a wasteful number, since it uses less digits than its factorization.

665801631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1396 (or 1393 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 665801631 is about 25803.1321935923. The cubic root of 665801631 is about 873.2024620664.

The spelling of 665801631 in words is "six hundred sixty-five million, eight hundred one thousand, six hundred thirty-one".