21572451 has 12 divisors (see below), whose sum is σ = 31555680. Its totient is φ = 14199120.

The previous prime is 21572417. The next prime is 21572477. The reversal of 21572451 is 15427512.

It is not a de Polignac number, because 21572451 - 2⁶ = 21572387 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21572401) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14460 + ... + 15881.

It is an arithmetic number, because the mean of its divisors is an integer number (2629640).

Almost surely, 2^21572451 is an apocalyptic number.

21572451 is a deficient number, since it is larger than the sum of its proper divisors (9983229).

21572451 is a wasteful number, since it uses less digits than its factorization.

21572451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30426 (or 30423 counting only the distinct ones).

The product of its digits is 2800, while the sum is 27.

The square root of 21572451 is about 4644.6152693199. The cubic root of 21572451 is about 278.3768804498.

Adding to 21572451 its reverse (15427512), we get a palindrome (36999963).

The spelling of 21572451 in words is "twenty-one million, five hundred seventy-two thousand, four hundred fifty-one".