21959424 has 108 divisors (see below), whose sum is σ = 65845416. Its totient is φ = 7299072.

The previous prime is 21959423. The next prime is 21959449. The reversal of 21959424 is 42495912.

It is a tau number, because it is divible by the number of its divisors (108).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nialpdrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (21959423) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 62032 + ... + 62384.

Almost surely, 2^21959424 is an apocalyptic number.

21959424 is a gapful number since it is divisible by the number (24) 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 21959424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32922708).

21959424 is an abundant number, since it is smaller than the sum of its proper divisors (43885992).

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

21959424 is an frugal number, since it uses more digits than its factorization.

21959424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 384 (or 358 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 21959424 is about 4686.0883474386. The cubic root of 21959424 is about 280.0315610682.

The spelling of 21959424 in words is "twenty-one million, nine hundred fifty-nine thousand, four hundred twenty-four".