66990856 has 8 divisors (see below), whose sum is σ = 125607870. Its totient is φ = 33495424.

The previous prime is 66990851. The next prime is 66990883. The reversal of 66990856 is 65809966.

It can be written as a sum of positive squares in only one way, i.e., 65124900 + 1865956 = 8070^2 + 1366^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×66990856² = 8975549575225472, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66990851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4186921 + ... + 4186936.

Almost surely, 2^66990856 is an apocalyptic number.

It is an amenable number.

66990856 is a deficient number, since it is larger than the sum of its proper divisors (58617014).

66990856 is a wasteful number, since it uses less digits than its factorization.

66990856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8373863 (or 8373859 counting only the distinct ones).

The product of its (nonzero) digits is 699840, while the sum is 49.

The square root of 66990856 is about 8184.7941941139. The cubic root of 66990856 is about 406.1363321911.

The spelling of 66990856 in words is "sixty-six million, nine hundred ninety thousand, eight hundred fifty-six".