21913680 has 160 divisors (see below), whose sum is σ = 74245248. Its totient is φ = 5324800.

The previous prime is 21913679. The next prime is 21913691. The reversal of 21913680 is 8631912.

21913680 = T₂₁₅ + T₂₁₆ + ... + T₅₂₀.

It is a super-2 number, since 2×21913680² = 960418742284800, 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 31 ways as a sum of consecutive naturals, for example, 167215 + ... + 167345.

Almost surely, 2^21913680 is an apocalyptic number.

21913680 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 21913680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37122624).

21913680 is an abundant number, since it is smaller than the sum of its proper divisors (52331568).

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

21913680 is a wasteful number, since it uses less digits than its factorization.

21913680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205 (or 199 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 21913680 is about 4681.2049730812. The cubic root of 21913680 is about 279.8369799357.

The spelling of 21913680 in words is "twenty-one million, nine hundred thirteen thousand, six hundred eighty".