640554960 has 80 divisors (see below), whose sum is σ = 1989444096. Its totient is φ = 170494464.

The previous prime is 640554919. The next prime is 640554973. The reversal of 640554960 is 69455046.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 143482 + ... + 147878.

Almost surely, 2^640554960 is an apocalyptic number.

640554960 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 640554960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (994722048).

640554960 is an abundant number, since it is smaller than the sum of its proper divisors (1348889136).

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

640554960 is a wasteful number, since it uses less digits than its factorization.

640554960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5020 (or 5014 counting only the distinct ones).

The product of its (nonzero) digits is 129600, while the sum is 39.

The square root of 640554960 is about 25309.1872647069. The cubic root of 640554960 is about 862.0228926079.

The spelling of 640554960 in words is "six hundred forty million, five hundred fifty-four thousand, nine hundred sixty".