64939840 has 112 divisors (see below), whose sum is σ = 180392832. Its totient is φ = 21805056.

The previous prime is 64939811. The next prime is 64939843. The reversal of 64939840 is 4893946.

It is a tau number, because it is divible by the number of its divisors (112).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64939843) 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, 118447 + ... + 118993.

Almost surely, 2^64939840 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 64939840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (90196416).

64939840 is an abundant number, since it is smaller than the sum of its proper divisors (115452992).

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

64939840 is a wasteful number, since it uses less digits than its factorization.

64939840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 624 (or 614 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 43.

The square root of 64939840 is about 8058.5259197945. The cubic root of 64939840 is about 401.9484930255.

The spelling of 64939840 in words is "sixty-four million, nine hundred thirty-nine thousand, eight hundred forty".