21928313 has 4 divisors (see below), whose sum is σ = 23921808. Its totient is φ = 19934820.

The previous prime is 21928303. The next prime is 21928327. The reversal of 21928313 is 31382912.

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 a de Polignac number, because none of the positive numbers 2^k-21928313 is a prime.

It is a super-2 number, since 2×21928313² = 961701822051938, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21928303) 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, 996731 + ... + 996752.

It is an arithmetic number, because the mean of its divisors is an integer number (5980452).

Almost surely, 2^21928313 is an apocalyptic number.

It is an amenable number.

21928313 is a deficient number, since it is larger than the sum of its proper divisors (1993495).

21928313 is a wasteful number, since it uses less digits than its factorization.

21928313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1993494.

The product of its digits is 2592, while the sum is 29.

The square root of 21928313 is about 4682.7676645334. The cubic root of 21928313 is about 279.8992537210.

The spelling of 21928313 in words is "twenty-one million, nine hundred twenty-eight thousand, three hundred thirteen".