21933840 has 80 divisors (see below), whose sum is σ = 69192000. Its totient is φ = 5746176.

The previous prime is 21933839. The next prime is 21933851. The reversal of 21933840 is 4833912.

It is a tau number, because it is divible by the number of its divisors (80).

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

It is a junction number, because it is equal to n+sod(n) for n = 21933798 and 21933807.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13386 + ... + 14934.

It is an arithmetic number, because the mean of its divisors is an integer number (864900).

Almost surely, 2^21933840 is an apocalyptic number.

21933840 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 21933840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34596000).

21933840 is an abundant number, since it is smaller than the sum of its proper divisors (47258160).

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

21933840 is a wasteful number, since it uses less digits than its factorization.

21933840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1624 (or 1618 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 30.

The square root of 21933840 is about 4683.3577698058. The cubic root of 21933840 is about 279.9227678147.

The spelling of 21933840 in words is "twenty-one million, nine hundred thirty-three thousand, eight hundred forty".