990421920 has 288 divisors, whose sum is σ = 3596458320. Its totient is φ = 247726080.

The previous prime is 990421919. The next prime is 990421931. The reversal of 990421920 is 29124099.

It can be written as a sum of positive squares in 8 ways, for example, as 852406416 + 138015504 = 29196^2 + 11748^2 .

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1544800 + ... + 1545440.

Almost surely, 2^990421920 is an apocalyptic number.

990421920 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 990421920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1798229160).

990421920 is an abundant number, since it is smaller than the sum of its proper divisors (2606036400).

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

990421920 is a wasteful number, since it uses less digits than its factorization.

990421920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 728 (or 717 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 36.

The square root of 990421920 is about 31470.9694798238. The cubic root of 990421920 is about 996.7970587871.

The spelling of 990421920 in words is "nine hundred ninety million, four hundred twenty-one thousand, nine hundred twenty".