641989920 has 384 divisors, whose sum is σ = 2438553600. Its totient is φ = 139898880.

The previous prime is 641989903. The next prime is 641989937. The reversal of 641989920 is 29989146.

It is an interprime number because it is at equal distance from previous prime (641989903) and next prime (641989937).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 641989920.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3225981 + ... + 3226179.

It is an arithmetic number, because the mean of its divisors is an integer number (6350400).

Almost surely, 2^641989920 is an apocalyptic number.

641989920 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 641989920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1219276800).

641989920 is an abundant number, since it is smaller than the sum of its proper divisors (1796563680).

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

641989920 is a wasteful number, since it uses less digits than its factorization.

641989920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 288 (or 280 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 48.

The square root of 641989920 is about 25337.5200049255. The cubic root of 641989920 is about 862.6661087338. Note that the first 3 decimals are identical.

The spelling of 641989920 in words is "six hundred forty-one million, nine hundred eighty-nine thousand, nine hundred twenty".