665631031 has 4 divisors (see below), whose sum is σ = 716833432. Its totient is φ = 614428632.

The previous prime is 665630993. The next prime is 665631067. The reversal of 665631031 is 130136566.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 665631031 - 2²¹ = 663533879 is a prime.

It is a super-2 number, since 2×665631031² = 886129338860245922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 665630984 and 665631002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665635031) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25601181 + ... + 25601206.

It is an arithmetic number, because the mean of its divisors is an integer number (179208358).

Almost surely, 2^665631031 is an apocalyptic number.

665631031 is a deficient number, since it is larger than the sum of its proper divisors (51202401).

665631031 is a wasteful number, since it uses less digits than its factorization.

665631031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51202400.

The product of its (nonzero) digits is 9720, while the sum is 31.

The square root of 665631031 is about 25799.8261815850. The cubic root of 665631031 is about 873.1278747527.

Adding to 665631031 its reverse (130136566), we get a palindrome (795767597).

The spelling of 665631031 in words is "six hundred sixty-five million, six hundred thirty-one thousand, thirty-one".