21976320 has 144 divisors (see below), whose sum is σ = 72112320. Its totient is φ = 5701632.

The previous prime is 21976319. The next prime is 21976321. The reversal of 21976320 is 2367912.

21976320 = T₂₄ + T₂₅ + ... + T₅₀₈.

It is an interprime number because it is at equal distance from previous prime (21976319) and next prime (21976321).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21976321) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 226512 + ... + 226608.

It is an arithmetic number, because the mean of its divisors is an integer number (500780).

Almost surely, 2^21976320 is an apocalyptic number.

21976320 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 21976320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36056160).

21976320 is an abundant number, since it is smaller than the sum of its proper divisors (50136000).

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

21976320 is an equidigital number, since it uses as much as digits as its factorization.

21976320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180 (or 166 counting only the distinct ones).

The product of its (nonzero) digits is 4536, while the sum is 30.

The square root of 21976320 is about 4687.8907837107. The cubic root of 21976320 is about 280.1033631989.

The spelling of 21976320 in words is "twenty-one million, nine hundred seventy-six thousand, three hundred twenty".