21225748 has 6 divisors (see below), whose sum is σ = 37145066. Its totient is φ = 10612872.

The previous prime is 21225739. The next prime is 21225749. The reversal of 21225748 is 84752212.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 20629764 + 595984 = 4542^2 + 772^2 .

It is a congruent number.

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 as a sum of consecutive naturals, namely, 2653215 + ... + 2653222.

Almost surely, 2^21225748 is an apocalyptic number.

It is an amenable number.

21225748 is a deficient number, since it is larger than the sum of its proper divisors (15919318).

21225748 is a wasteful number, since it uses less digits than its factorization.

21225748 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5306441 (or 5306439 counting only the distinct ones).

The product of its digits is 8960, while the sum is 31.

The square root of 21225748 is about 4607.1409789586. The cubic root of 21225748 is about 276.8775019095.

The spelling of 21225748 in words is "twenty-one million, two hundred twenty-five thousand, seven hundred forty-eight".