64138720 has 96 divisors (see below), whose sum is σ = 163840320. Its totient is φ = 23654400.

The previous prime is 64138703. The next prime is 64138727. The reversal of 64138720 is 2783146.

It is a super-2 number, since 2×64138720² = 8227550806476800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64138727) 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, 106420 + ... + 107020.

It is an arithmetic number, because the mean of its divisors is an integer number (1706670).

Almost surely, 2^64138720 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 64138720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (81920160).

64138720 is an abundant number, since it is smaller than the sum of its proper divisors (99701600).

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

64138720 is a wasteful number, since it uses less digits than its factorization.

64138720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 668 (or 660 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 31.

The square root of 64138720 is about 8008.6653070284. The cubic root of 64138720 is about 400.2887914486.

The spelling of 64138720 in words is "sixty-four million, one hundred thirty-eight thousand, seven hundred twenty".