21530253 has 8 divisors (see below), whose sum is σ = 29111616. Its totient is φ = 14151200.

The previous prime is 21530251. The next prime is 21530261. The reversal of 21530253 is 35203512.

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

It is a cyclic number.

It is not a de Polignac number, because 21530253 - 2¹ = 21530251 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21530251) 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, 50328 + ... + 50753.

It is an arithmetic number, because the mean of its divisors is an integer number (3638952).

Almost surely, 2^21530253 is an apocalyptic number.

It is an amenable number.

21530253 is a deficient number, since it is larger than the sum of its proper divisors (7581363).

21530253 is a wasteful number, since it uses less digits than its factorization.

21530253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101155.

The product of its (nonzero) digits is 900, while the sum is 21.

The square root of 21530253 is about 4640.0703658458. The cubic root of 21530253 is about 278.1952504106.

Adding to 21530253 its reverse (35203512), we get a palindrome (56733765).

The spelling of 21530253 in words is "twenty-one million, five hundred thirty thousand, two hundred fifty-three".