64637440 has 80 divisors (see below), whose sum is σ = 177167232. Its totient is φ = 22155264.

The previous prime is 64637431. The next prime is 64637459. The reversal of 64637440 is 4473646.

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 64637396 and 64637405.

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, 16117 + ... + 19723.

Almost surely, 2^64637440 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 64637440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88583616).

64637440 is an abundant number, since it is smaller than the sum of its proper divisors (112529792).

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

64637440 is an equidigital number, since it uses as much as digits as its factorization.

64637440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3637 (or 3621 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 34.

The square root of 64637440 is about 8039.7412893700. The cubic root of 64637440 is about 401.3236152754.

The spelling of 64637440 in words is "sixty-four million, six hundred thirty-seven thousand, four hundred forty".