21912744 has 128 divisors (see below), whose sum is σ = 67184640. Its totient is φ = 5820672.

The previous prime is 21912733. The next prime is 21912773. The reversal of 21912744 is 44721912.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 204739 + ... + 204845.

It is an arithmetic number, because the mean of its divisors is an integer number (524880).

Almost surely, 2^21912744 is an apocalyptic number.

21912744 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 21912744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33592320).

21912744 is an abundant number, since it is smaller than the sum of its proper divisors (45271896).

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

21912744 is a wasteful number, since it uses less digits than its factorization.

21912744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199 (or 195 counting only the distinct ones).

The product of its digits is 4032, while the sum is 30.

The square root of 21912744 is about 4681.1049977543. The cubic root of 21912744 is about 279.8329956491.

The spelling of 21912744 in words is "twenty-one million, nine hundred twelve thousand, seven hundred forty-four".