66865720 has 16 divisors (see below), whose sum is σ = 150447960. Its totient is φ = 26746272.

The previous prime is 66865717. The next prime is 66865739. The reversal of 66865720 is 2756866.

It is a super-2 number, since 2×66865720² = 8942049022236800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (40), and also a Moran number because the ratio is a prime number: 1671643 = 66865720 / (6 + 6 + 8 + 6 + 5 + 7 + 2 + 0).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 835782 + ... + 835861.

Almost surely, 2^66865720 is an apocalyptic number.

It is an amenable number.

66865720 is an abundant number, since it is smaller than the sum of its proper divisors (83582240).

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

66865720 is a wasteful number, since it uses less digits than its factorization.

66865720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1671654 (or 1671650 counting only the distinct ones).

The product of its (nonzero) digits is 120960, while the sum is 40.

The square root of 66865720 is about 8177.1462014568. The cubic root of 66865720 is about 405.8832929129.

The spelling of 66865720 in words is "sixty-six million, eight hundred sixty-five thousand, seven hundred twenty".