23121920 has 52 divisors (see below), whose sum is σ = 55534980. Its totient is φ = 9240576.

The previous prime is 23121919. The next prime is 23121941. The reversal of 23121920 is 2912132.

It can be written as a sum of positive squares in 2 ways, for example, as 4734976 + 18386944 = 2176^2 + 4288^2 .

It is a hoax number, since the sum of its digits (20) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 23121892 and 23121901.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19916 + ... + 21044.

Almost surely, 2^23121920 is an apocalyptic number.

23121920 is a gapful number since it is divisible by the number (20) 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 23121920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27767490).

23121920 is an abundant number, since it is smaller than the sum of its proper divisors (32413060).

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

23121920 is an equidigital number, since it uses as much as digits as its factorization.

23121920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1158 (or 1136 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 23121920 is about 4808.5257616030. The cubic root of 23121920 is about 284.8883116277. Note that the first 3 decimals are identical.

The spelling of 23121920 in words is "twenty-three million, one hundred twenty-one thousand, nine hundred twenty".