21252553 has 8 divisors (see below), whose sum is σ = 24405440. Its totient is φ = 18128880.

The previous prime is 21252551. The next prime is 21252571. The reversal of 21252553 is 35525212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21252553 - 2¹ = 21252551 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21252551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5718 + ... + 8671.

It is an arithmetic number, because the mean of its divisors is an integer number (3050680).

Almost surely, 2^21252553 is an apocalyptic number.

It is an amenable number.

21252553 is a deficient number, since it is larger than the sum of its proper divisors (3152887).

21252553 is a wasteful number, since it uses less digits than its factorization.

21252553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14607.

The product of its digits is 3000, while the sum is 25.

The square root of 21252553 is about 4610.0491320592. The cubic root of 21252553 is about 276.9940047445.

Adding to 21252553 its reverse (35525212), we get a palindrome (56777765).

The spelling of 21252553 in words is "twenty-one million, two hundred fifty-two thousand, five hundred fifty-three".