640021140 has 72 divisors (see below), whose sum is σ = 2117894688. Its totient is φ = 155156160.

The previous prime is 640021121. The next prime is 640021177. The reversal of 640021140 is 41120046.

640021140 is a `hidden beast` number, since 640 + 0 + 21 + 1 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 159642 + ... + 163601.

It is an arithmetic number, because the mean of its divisors is an integer number (29415204).

Almost surely, 2^640021140 is an apocalyptic number.

640021140 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

640021140 is an abundant number, since it is smaller than the sum of its proper divisors (1477873548).

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

640021140 is a wasteful number, since it uses less digits than its factorization.

640021140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 323269 (or 323264 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 640021140 is about 25298.6390938327. The cubic root of 640021140 is about 861.7833643977.

Adding to 640021140 its reverse (41120046), we get a palindrome (681141186).

The spelling of 640021140 in words is "six hundred forty million, twenty-one thousand, one hundred forty".