21983840 has 24 divisors (see below), whose sum is σ = 51937200. Its totient is φ = 8793472.

The previous prime is 21983807. The next prime is 21983861. The reversal of 21983840 is 4838912.

It is a happy number.

It is a super-2 number, since 2×21983840² = 966578442291200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21983840.

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, 68540 + ... + 68859.

It is an arithmetic number, because the mean of its divisors is an integer number (2164050).

Almost surely, 2^21983840 is an apocalyptic number.

21983840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21983840 is an abundant number, since it is smaller than the sum of its proper divisors (29953360).

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

21983840 is a wasteful number, since it uses less digits than its factorization.

21983840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137414 (or 137406 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 35.

The square root of 21983840 is about 4688.6927815757. The cubic root of 21983840 is about 280.1353087518.

The spelling of 21983840 in words is "twenty-one million, nine hundred eighty-three thousand, eight hundred forty".