21545744 has 60 divisors (see below), whose sum is σ = 47496960. Its totient is φ = 9451200.

The previous prime is 21545723. The next prime is 21545759. The reversal of 21545744 is 44754512.

It is a self number, because there is not a number n which added to its sum of digits gives 21545744.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 59837 + ... + 60195.

It is an arithmetic number, because the mean of its divisors is an integer number (791616).

Almost surely, 2^21545744 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 21545744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23748480).

21545744 is an abundant number, since it is smaller than the sum of its proper divisors (25951216).

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

21545744 is a wasteful number, since it uses less digits than its factorization.

21545744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 420 (or 403 counting only the distinct ones).

The product of its digits is 22400, while the sum is 32.

The square root of 21545744 is about 4641.7393291739. The cubic root of 21545744 is about 278.2619548361.

The spelling of 21545744 in words is "twenty-one million, five hundred forty-five thousand, seven hundred forty-four".