21909344 has 48 divisors (see below), whose sum is σ = 44643312. Its totient is φ = 10579968.

The previous prime is 21909341. The next prime is 21909347. The reversal of 21909344 is 44390912.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21909341) and next prime (21909347).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a self number, because there is not a number n which added to its sum of digits gives 21909344.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21909341) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 193832 + ... + 193944.

It is an arithmetic number, because the mean of its divisors is an integer number (930069).

Almost surely, 2^21909344 is an apocalyptic number.

It is an amenable number.

21909344 is an abundant number, since it is smaller than the sum of its proper divisors (22733968).

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

21909344 is a wasteful number, since it uses less digits than its factorization.

21909344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 279 (or 271 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 21909344 is about 4680.7418215492. The cubic root of 21909344 is about 279.8185218586.

The spelling of 21909344 in words is "twenty-one million, nine hundred nine thousand, three hundred forty-four".