66657994 has 36 divisors (see below), whose sum is σ = 112150818. Its totient is φ = 29689920.

The previous prime is 66657991. The next prime is 66658001. The reversal of 66657994 is 49975666.

It can be written as a sum of positive squares in 9 ways, for example, as 14630625 + 52027369 = 3825^2 + 7213^2 .

It is not an unprimeable number, because it can be changed into a prime (66657991) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1092724 + ... + 1092784.

Almost surely, 2^66657994 is an apocalyptic number.

66657994 is a deficient number, since it is larger than the sum of its proper divisors (45492824).

66657994 is a wasteful number, since it uses less digits than its factorization.

66657994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203 (or 129 counting only the distinct ones).

The product of its digits is 2449440, while the sum is 52.

The square root of 66657994 is about 8164.4347018027. The cubic root of 66657994 is about 405.4625493055.

The spelling of 66657994 in words is "sixty-six million, six hundred fifty-seven thousand, nine hundred ninety-four".