640556100 has 180 divisors, whose sum is σ = 2144251648. Its totient is φ = 165240000.

The previous prime is 640556083. The next prime is 640556117. The reversal of 640556100 is 1655046.

It is a happy number.

640556100 is a `hidden beast` number, since 6 + 4 + 0 + 556 + 100 = 666.

It is an interprime number because it is at equal distance from previous prime (640556083) and next prime (640556117).

It is a tau number, because it is divible by the number of its divisors (180).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 249825 + ... + 252375.

Almost surely, 2^640556100 is an apocalyptic number.

640556100 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 640556100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1072125824).

640556100 is an abundant number, since it is smaller than the sum of its proper divisors (1503695548).

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

640556100 is a wasteful number, since it uses less digits than its factorization.

640556100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2608 (or 2592 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 640556100 is about 25309.2097861628. The cubic root of 640556100 is about 862.0234039902.

The spelling of 640556100 in words is "six hundred forty million, five hundred fifty-six thousand, one hundred".