21426944 has 72 divisors (see below), whose sum is σ = 53372928. Its totient is φ = 8340480.

The previous prime is 21426931. The next prime is 21426973. The reversal of 21426944 is 44962412.

It is a super-2 number, since 2×21426944² = 918227858358272, which contains 22 as substring.

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 21426944.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19169 + ... + 20255.

Almost surely, 2^21426944 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21426944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26686464).

21426944 is an abundant number, since it is smaller than the sum of its proper divisors (31945984).

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

21426944 is a wasteful number, since it uses less digits than its factorization.

21426944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1121 (or 1107 counting only the distinct ones).

The product of its digits is 13824, while the sum is 32.

The square root of 21426944 is about 4628.9247131488. The cubic root of 21426944 is about 277.7495804030.

The spelling of 21426944 in words is "twenty-one million, four hundred twenty-six thousand, nine hundred forty-four".