665124381 has 12 divisors (see below), whose sum is σ = 960958908. Its totient is φ = 443313024.

The previous prime is 665124359. The next prime is 665124391. The reversal of 665124381 is 183421566.

It is a happy number.

665124381 is a `hidden beast` number, since 66 + 512 + 4 + 3 + 81 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 338744025 + 326380356 = 18405^2 + 18066^2 .

It is not a de Polignac number, because 665124381 - 2⁵ = 665124349 is a prime.

It is a super-2 number, since 2×665124381² = 884780884401266322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665124391) 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, 69991 + ... + 78923.

It is an arithmetic number, because the mean of its divisors is an integer number (80079909).

Almost surely, 2^665124381 is an apocalyptic number.

It is an amenable number.

665124381 is a deficient number, since it is larger than the sum of its proper divisors (295834527).

665124381 is a wasteful number, since it uses less digits than its factorization.

665124381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17212 (or 17209 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 665124381 is about 25790.0054478474. The cubic root of 665124381 is about 872.9062892684.

The spelling of 665124381 in words is "six hundred sixty-five million, one hundred twenty-four thousand, three hundred eighty-one".