640872078 has 96 divisors (see below), whose sum is σ = 1657687680. Its totient is φ = 163275840.

The previous prime is 640872053. The next prime is 640872091. The reversal of 640872078 is 870278046.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 169533 + ... + 173271.

It is an arithmetic number, because the mean of its divisors is an integer number (17267580).

Almost surely, 2^640872078 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640872078, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (828843840).

640872078 is an abundant number, since it is smaller than the sum of its proper divisors (1016815602).

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

640872078 is a wasteful number, since it uses less digits than its factorization.

640872078 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3822 (or 3815 counting only the distinct ones).

The product of its (nonzero) digits is 150528, while the sum is 42.

The square root of 640872078 is about 25315.4513686800. The cubic root of 640872078 is about 862.1651223378.

The spelling of 640872078 in words is "six hundred forty million, eight hundred seventy-two thousand, seventy-eight".