64639940 has 24 divisors (see below), whose sum is σ = 136321920. Its totient is φ = 25745888.

The previous prime is 64639921. The next prime is 64639951. The reversal of 64639940 is 4993646.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1982 + ... + 11541.

It is an arithmetic number, because the mean of its divisors is an integer number (5680080).

Almost surely, 2^64639940 is an apocalyptic number.

It is an amenable number.

64639940 is an abundant number, since it is smaller than the sum of its proper divisors (71681980).

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

64639940 is a wasteful number, since it uses less digits than its factorization.

64639940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13771 (or 13769 counting only the distinct ones).

The product of its (nonzero) digits is 139968, while the sum is 41.

The square root of 64639940 is about 8039.8967655064. The cubic root of 64639940 is about 401.3287892432.

The spelling of 64639940 in words is "sixty-four million, six hundred thirty-nine thousand, nine hundred forty".