21224572 has 6 divisors (see below), whose sum is σ = 37143008. Its totient is φ = 10612284.

The previous prime is 21224563. The next prime is 21224579. The reversal of 21224572 is 27542212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21224579) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2653068 + ... + 2653075.

Almost surely, 2^21224572 is an apocalyptic number.

It is an amenable number.

21224572 is a deficient number, since it is larger than the sum of its proper divisors (15918436).

21224572 is a wasteful number, since it uses less digits than its factorization.

21224572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5306147 (or 5306145 counting only the distinct ones).

The product of its digits is 2240, while the sum is 25.

The square root of 21224572 is about 4607.0133492318. The cubic root of 21224572 is about 276.8723884037.

Adding to 21224572 its reverse (27542212), we get a palindrome (48766784).

It can be divided in two parts, 21224 and 572, that multiplied together give a triangular number (12140128 = T₄₉₂₇).

The spelling of 21224572 in words is "twenty-one million, two hundred twenty-four thousand, five hundred seventy-two".