640417860 has 96 divisors (see below), whose sum is σ = 2026281600. Its totient is φ = 167875200.

The previous prime is 640417859. The next prime is 640417873. The reversal of 640417860 is 68714046.

640417860 is a `hidden beast` number, since 640 + 4 + 1 + 7 + 8 + 6 + 0 = 666.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 21810 + ... + 41910.

It is an arithmetic number, because the mean of its divisors is an integer number (21107100).

Almost surely, 2^640417860 is an apocalyptic number.

640417860 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640417860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1013140800).

640417860 is an abundant number, since it is smaller than the sum of its proper divisors (1385863740).

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

640417860 is a wasteful number, since it uses less digits than its factorization.

640417860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20178 (or 20170 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 36.

The square root of 640417860 is about 25306.4786171447. The cubic root of 640417860 is about 861.9613877261.

The spelling of 640417860 in words is "six hundred forty million, four hundred seventeen thousand, eight hundred sixty".