990404288640 has 640 divisors, whose sum is σ = 3931936081920. Its totient is φ = 235922595840.

The previous prime is 990404288597. The next prime is 990404288681. The reversal of 990404288640 is 46882404099.

It is a tau number, because it is divible by the number of its divisors (640).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 20867817 + ... + 20915223.

It is an arithmetic number, because the mean of its divisors is an integer number (6143650128).

Almost surely, 2^990404288640 is an apocalyptic number.

990404288640 is a gapful number since it is divisible by the number (90) 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 990404288640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1965968040960).

990404288640 is an abundant number, since it is smaller than the sum of its proper divisors (2941531793280).

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

990404288640 is a wasteful number, since it uses less digits than its factorization.

990404288640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47482 (or 47461 counting only the distinct ones).

The product of its (nonzero) digits is 3981312, while the sum is 54.

The spelling of 990404288640 in words is "nine hundred ninety billion, four hundred four million, two hundred eighty-eight thousand, six hundred forty".