21943440 has 80 divisors (see below), whose sum is σ = 75590400. Its totient is φ = 5851008.

The previous prime is 21943421. The next prime is 21943483. The reversal of 21943440 is 4434912.

21943440 is a `hidden beast` number, since 219 + 4 + 3 + 440 = 666.

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 (27).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2920 + ... + 7239.

It is an arithmetic number, because the mean of its divisors is an integer number (944880).

Almost surely, 2^21943440 is an apocalyptic number.

21943440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21943440 is an abundant number, since it is smaller than the sum of its proper divisors (53646960).

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

21943440 is a wasteful number, since it uses less digits than its factorization.

21943440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10181 (or 10169 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 21943440 is about 4684.3825633695. The cubic root of 21943440 is about 279.9636007106.

The spelling of 21943440 in words is "twenty-one million, nine hundred forty-three thousand, four hundred forty".