665623431 has 24 divisors (see below), whose sum is σ = 1059261840. Its totient is φ = 399408000.

The previous prime is 665623393. The next prime is 665623463. The reversal of 665623431 is 134326566.

665623431 is a `hidden beast` number, since 66 + 562 + 3 + 4 + 31 = 666.

It is a de Polignac number, because none of the positive numbers 2^k-665623431 is a prime.

It is a super-2 number, since 2×665623431² = 886109103792423522, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665623031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 23286 + ... + 43283.

It is an arithmetic number, because the mean of its divisors is an integer number (44135910).

Almost surely, 2^665623431 is an apocalyptic number.

665623431 is a deficient number, since it is larger than the sum of its proper divisors (393638409).

665623431 is a wasteful number, since it uses less digits than its factorization.

665623431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66687 (or 66684 counting only the distinct ones).

The product of its digits is 77760, while the sum is 36.

The square root of 665623431 is about 25799.6788933506. The cubic root of 665623431 is about 873.1245516919.

Adding to 665623431 its reverse (134326566), we get a palindrome (799949997).

The spelling of 665623431 in words is "six hundred sixty-five million, six hundred twenty-three thousand, four hundred thirty-one".