21252279 has 8 divisors (see below), whose sum is σ = 29827840. Its totient is φ = 13422456.

The previous prime is 21252269. The next prime is 21252281. The reversal of 21252279 is 97225212.

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

It is not a de Polignac number, because 21252279 - 2⁵ = 21252247 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 (21252239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 186367 + ... + 186480.

It is an arithmetic number, because the mean of its divisors is an integer number (3728480).

Almost surely, 2^21252279 is an apocalyptic number.

21252279 is a deficient number, since it is larger than the sum of its proper divisors (8575561).

21252279 is a wasteful number, since it uses less digits than its factorization.

21252279 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 372869.

The product of its digits is 5040, while the sum is 30.

The square root of 21252279 is about 4610.0194142758. The cubic root of 21252279 is about 276.9928143513.

The spelling of 21252279 in words is "twenty-one million, two hundred fifty-two thousand, two hundred seventy-nine".