666811507 has 4 divisors (see below), whose sum is σ = 668137680. Its totient is φ = 665485336.

The previous prime is 666811501. The next prime is 666811549. The reversal of 666811507 is 705118666.

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 666811507 - 2²⁷ = 532593779 is a prime.

It is a super-2 number, since 2×666811507² = 889275171735222098, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 666811507.

It is not an unprimeable number, because it can be changed into a prime (666811501) 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, 662332 + ... + 663337.

It is an arithmetic number, because the mean of its divisors is an integer number (167034420).

Almost surely, 2^666811507 is an apocalyptic number.

666811507 is a deficient number, since it is larger than the sum of its proper divisors (1326173).

666811507 is a wasteful number, since it uses less digits than its factorization.

666811507 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1326172.

The product of its (nonzero) digits is 60480, while the sum is 40.

The square root of 666811507 is about 25822.6936433828. The cubic root of 666811507 is about 873.6437249981.

The spelling of 666811507 in words is "six hundred sixty-six million, eight hundred eleven thousand, five hundred seven".