21219744 has 144 divisors (see below), whose sum is σ = 69981408. Its totient is φ = 5580288.

The previous prime is 21219727. The next prime is 21219749. The reversal of 21219744 is 44791212.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21219749) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 60979 + ... + 61325.

It is an arithmetic number, because the mean of its divisors is an integer number (485982).

Almost surely, 2^21219744 is an apocalyptic number.

21219744 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 21219744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34990704).

21219744 is an abundant number, since it is smaller than the sum of its proper divisors (48761664).

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

21219744 is a wasteful number, since it uses less digits than its factorization.

21219744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 387 (or 372 counting only the distinct ones).

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

The square root of 21219744 is about 4606.4893357089. The cubic root of 21219744 is about 276.8513932216.

The spelling of 21219744 in words is "twenty-one million, two hundred nineteen thousand, seven hundred forty-four".