666451531 has 4 divisors (see below), whose sum is σ = 669312072. Its totient is φ = 663590992.

The previous prime is 666451507. The next prime is 666451553. The reversal of 666451531 is 135154666.

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 666451531 - 2⁷ = 666451403 is a prime.

It is a super-2 number, since 2×666451531² = 888315286344487922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (666451501) 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, 1429921 + ... + 1430386.

It is an arithmetic number, because the mean of its divisors is an integer number (167328018).

Almost surely, 2^666451531 is an apocalyptic number.

666451531 is a deficient number, since it is larger than the sum of its proper divisors (2860541).

666451531 is a wasteful number, since it uses less digits than its factorization.

666451531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2860540.

The product of its digits is 64800, while the sum is 37.

The square root of 666451531 is about 25815.7225542885. The cubic root of 666451531 is about 873.4864854686.

The spelling of 666451531 in words is "six hundred sixty-six million, four hundred fifty-one thousand, five hundred thirty-one".