921391920 has 120 divisors (see below), whose sum is σ = 3194236032. Its totient is φ = 237772800.

The previous prime is 921391907. The next prime is 921391927. The reversal of 921391920 is 29193129.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (120).

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

It is not an unprimeable number, because it can be changed into a prime (921391927) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1680 + ... + 42960.

Almost surely, 2^921391920 is an apocalyptic number.

921391920 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 921391920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1597118016).

921391920 is an abundant number, since it is smaller than the sum of its proper divisors (2272844112).

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

921391920 is a wasteful number, since it uses less digits than its factorization.

921391920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41331 (or 41322 counting only the distinct ones).

The product of its (nonzero) digits is 8748, while the sum is 36.

The square root of 921391920 is about 30354.4382257356. The cubic root of 921391920 is about 973.0790739300.

The spelling of 921391920 in words is "nine hundred twenty-one million, three hundred ninety-one thousand, nine hundred twenty".