21982080 has 96 divisors (see below), whose sum is σ = 70728840. Its totient is φ = 5807104.

The previous prime is 21982067. The next prime is 21982091. The reversal of 21982080 is 8028912.

It is a tau number, because it is divible by the number of its divisors (96).

It is a super-2 number, since 2×21982080² = 966423682252800, which contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 205387 + ... + 205493.

Almost surely, 2^21982080 is an apocalyptic number.

21982080 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 21982080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35364420).

21982080 is an abundant number, since it is smaller than the sum of its proper divisors (48746760).

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

21982080 is an equidigital number, since it uses as much as digits as its factorization.

21982080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 236 (or 117 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 30.

The square root of 21982080 is about 4688.5050922442. The cubic root of 21982080 is about 280.1278327861.

Multiplying 21982080 by its sum of digits (30), we get a square (659462400 = 25680²).

21982080 divided by its sum of digits (30) gives a square (732736 = 856²).

It can be divided in two parts, 2198 and 2080, that added together give a triangular number (4278 = T₉₂).

The spelling of 21982080 in words is "twenty-one million, nine hundred eighty-two thousand, eighty".