21225744 has 30 divisors (see below), whose sum is σ = 59403006. Its totient is φ = 7075200.

The previous prime is 21225739. The next prime is 21225749. The reversal of 21225744 is 44752212.

It is an interprime number because it is at equal distance from previous prime (21225739) and next prime (21225749).

It can be written as a sum of positive squares in only one way, i.e., 17539344 + 3686400 = 4188^2 + 1920^2 .

It is not an unprimeable number, because it can be changed into a prime (21225749) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 73557 + ... + 73844.

Almost surely, 2^21225744 is an apocalyptic number.

21225744 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21225744 is an abundant number, since it is smaller than the sum of its proper divisors (38177262).

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

21225744 is a wasteful number, since it uses less digits than its factorization.

21225744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147415 (or 147406 counting only the distinct ones).

The product of its digits is 4480, while the sum is 27.

The square root of 21225744 is about 4607.1405448499. The cubic root of 21225744 is about 276.8774845169.

Adding to 21225744 its reverse (44752212), we get a palindrome (65977956).

The spelling of 21225744 in words is "twenty-one million, two hundred twenty-five thousand, seven hundred forty-four".