21252613 has 4 divisors (see below), whose sum is σ = 21267360. Its totient is φ = 21237868.

The previous prime is 21252611. The next prime is 21252617. The reversal of 21252613 is 31625212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21252613 - 2¹ = 21252611 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21252611) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4945 + ... + 8182.

It is an arithmetic number, because the mean of its divisors is an integer number (5316840).

Almost surely, 2^21252613 is an apocalyptic number.

It is an amenable number.

21252613 is a deficient number, since it is larger than the sum of its proper divisors (14747).

21252613 is a wasteful number, since it uses less digits than its factorization.

21252613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14746.

The product of its digits is 720, while the sum is 22.

The square root of 21252613 is about 4610.0556395775. The cubic root of 21252613 is about 276.9942654132.

Adding to 21252613 its reverse (31625212), we get a palindrome (52877825).

It can be divided in two parts, 212 and 52613, that added together give a palindrome (52825).

The spelling of 21252613 in words is "twenty-one million, two hundred fifty-two thousand, six hundred thirteen".