21465424 has 40 divisors (see below), whose sum is σ = 44896680. Its totient is φ = 9904128.

The previous prime is 21465397. The next prime is 21465443. The reversal of 21465424 is 42456412.

It can be written as a sum of positive squares in 4 ways, for example, as 4981824 + 16483600 = 2232^2 + 4060^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21465392 and 21465401.

It is a congruent number.

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, 13672 + ... + 15160.

It is an arithmetic number, because the mean of its divisors is an integer number (1122417).

Almost surely, 2^21465424 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 21465424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22448340).

21465424 is an abundant number, since it is smaller than the sum of its proper divisors (23431256).

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

21465424 is a wasteful number, since it uses less digits than its factorization.

21465424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1567 (or 1561 counting only the distinct ones).

The product of its digits is 7680, while the sum is 28.

The square root of 21465424 is about 4633.0793215744. The cubic root of 21465424 is about 277.9157483247.

The spelling of 21465424 in words is "twenty-one million, four hundred sixty-five thousand, four hundred twenty-four".