64566640 has 20 divisors (see below), whose sum is σ = 150117624. Its totient is φ = 25826624.

The previous prime is 64566611. The next prime is 64566653. The reversal of 64566640 is 4666546.

It is a tau number, because it is divible by the number of its divisors (20).

It is a self number, because there is not a number n which added to its sum of digits gives 64566640.

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, 403462 + ... + 403621.

Almost surely, 2^64566640 is an apocalyptic number.

It is an amenable number.

64566640 is an abundant number, since it is smaller than the sum of its proper divisors (85550984).

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

64566640 is a wasteful number, since it uses less digits than its factorization.

64566640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 807096 (or 807090 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 37.

The square root of 64566640 is about 8035.3369562203. The cubic root of 64566640 is about 401.1770330856.

The spelling of 64566640 in words is "sixty-four million, five hundred sixty-six thousand, six hundred forty".