640721828100 has 288 divisors, whose sum is σ = 1993565903616. Its totient is φ = 158300979200.

The previous prime is 640721828099. The next prime is 640721828137. The reversal of 640721828100 is 1828127046.

It is a happy number.

It is a super-2 number, since 2×640721828100² (a number of 24 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 397222894 + ... + 397224506.

It is an arithmetic number, because the mean of its divisors is an integer number (6922103832).

Almost surely, 2^640721828100 is an apocalyptic number.

640721828100 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 640721828100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (996782951808).

640721828100 is an abundant number, since it is smaller than the sum of its proper divisors (1352844075516).

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

640721828100 is a wasteful number, since it uses less digits than its factorization.

640721828100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2815 (or 2808 counting only the distinct ones).

The product of its (nonzero) digits is 43008, while the sum is 39.

The spelling of 640721828100 in words is "six hundred forty billion, seven hundred twenty-one million, eight hundred twenty-eight thousand, one hundred".