666693881 has 4 divisors (see below), whose sum is σ = 761935872. Its totient is φ = 571451892.

The previous prime is 666693857. The next prime is 666693899. The reversal of 666693881 is 188396666.

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 666693881 - 2⁶ = 666693817 is a prime.

It is a super-2 number, since 2×666693881² = 888961461925684322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666693821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47620985 + ... + 47620998.

It is an arithmetic number, because the mean of its divisors is an integer number (190483968).

Almost surely, 2^666693881 is an apocalyptic number.

It is an amenable number.

666693881 is a deficient number, since it is larger than the sum of its proper divisors (95241991).

666693881 is an equidigital number, since it uses as much as digits as its factorization.

666693881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95241990.

The product of its digits is 2239488, while the sum is 53.

The square root of 666693881 is about 25820.4159726368. The cubic root of 666693881 is about 873.5923515295.

The spelling of 666693881 in words is "six hundred sixty-six million, six hundred ninety-three thousand, eight hundred eighty-one".