21152279 has 4 divisors (see below), whose sum is σ = 21164784. Its totient is φ = 21139776.

The previous prime is 21152239. The next prime is 21152291. The reversal of 21152279 is 97225112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21152279 - 2¹⁶ = 21086743 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 (21152239) 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, 3227 + ... + 7260.

It is an arithmetic number, because the mean of its divisors is an integer number (5291196).

Almost surely, 2^21152279 is an apocalyptic number.

21152279 is a deficient number, since it is larger than the sum of its proper divisors (12505).

21152279 is a wasteful number, since it uses less digits than its factorization.

21152279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12504.

The product of its digits is 2520, while the sum is 29.

The square root of 21152279 is about 4599.1606842988. The cubic root of 21152279 is about 276.5576792057.

The spelling of 21152279 in words is "twenty-one million, one hundred fifty-two thousand, two hundred seventy-nine".