64644040 has 32 divisors (see below), whose sum is σ = 146898360. Its totient is φ = 25600000.

The previous prime is 64644031. The next prime is 64644043. The reversal of 64644040 is 4044646.

It can be written as a sum of positive squares in 4 ways, for example, as 64609444 + 34596 = 8038^2 + 186^2 .

It is not an unprimeable number, because it can be changed into a prime (64644043) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3961 + ... + 12040.

Almost surely, 2^64644040 is an apocalyptic number.

It is an amenable number.

64644040 is an abundant number, since it is smaller than the sum of its proper divisors (82254320).

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

64644040 is a wasteful number, since it uses less digits than its factorization.

64644040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16113 (or 16109 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 28.

The square root of 64644040 is about 8040.1517398616. The cubic root of 64644040 is about 401.3372742617.

Adding to 64644040 its reverse (4044646), we get a palindrome (68688686).

The spelling of 64644040 in words is "sixty-four million, six hundred forty-four thousand, forty".