666634181 has 4 divisors (see below), whose sum is σ = 667770432. Its totient is φ = 665497932.

The previous prime is 666634151. The next prime is 666634187. The reversal of 666634181 is 181436666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 666634181 - 2¹⁴ = 666617797 is a prime.

It is a super-2 number, since 2×666634181² = 888802262555081522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666634187) 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, 567245 + ... + 568418.

It is an arithmetic number, because the mean of its divisors is an integer number (166942608).

Almost surely, 2^666634181 is an apocalyptic number.

It is an amenable number.

666634181 is a deficient number, since it is larger than the sum of its proper divisors (1136251).

666634181 is a wasteful number, since it uses less digits than its factorization.

666634181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1136250.

The product of its digits is 124416, while the sum is 41.

The square root of 666634181 is about 25819.2598848224. The cubic root of 666634181 is about 873.5662750839.

The spelling of 666634181 in words is "six hundred sixty-six million, six hundred thirty-four thousand, one hundred eighty-one".