64638540 has 48 divisors (see below), whose sum is σ = 201099360. Its totient is φ = 17236800.

The previous prime is 64638523. The next prime is 64638547. The reversal of 64638540 is 4583646.

64638540 is a `hidden beast` number, since 646 + 3 + 8 + 5 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 64638495 and 64638504.

It is not an unprimeable number, because it can be changed into a prime (64638547) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 59311 + ... + 60390.

It is an arithmetic number, because the mean of its divisors is an integer number (4189570).

Almost surely, 2^64638540 is an apocalyptic number.

64638540 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

64638540 is an abundant number, since it is smaller than the sum of its proper divisors (136460820).

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

64638540 is a wasteful number, since it uses less digits than its factorization.

64638540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119719 (or 119711 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 36.

The square root of 64638540 is about 8039.8096992404. The cubic root of 64638540 is about 401.3258918377.

The spelling of 64638540 in words is "sixty-four million, six hundred thirty-eight thousand, five hundred forty".