66900640 has 24 divisors (see below), whose sum is σ = 158053140. Its totient is φ = 26760192.

The previous prime is 66900619. The next prime is 66900649. The reversal of 66900640 is 4600966.

It can be written as a sum of positive squares in 2 ways, for example, as 62916624 + 3984016 = 7932^2 + 1996^2 .

It is not an unprimeable number, because it can be changed into a prime (66900649) 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, 208905 + ... + 209224.

Almost surely, 2^66900640 is an apocalyptic number.

It is an amenable number.

66900640 is an abundant number, since it is smaller than the sum of its proper divisors (91152500).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66900640 is a wasteful number, since it uses less digits than its factorization.

66900640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 418144 (or 418136 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 66900640 is about 8179.2811420075. The cubic root of 66900640 is about 405.9539368741.

The spelling of 66900640 in words is "sixty-six million, nine hundred thousand, six hundred forty".