21726319 has 4 divisors (see below), whose sum is σ = 22427200. Its totient is φ = 21025440.

The previous prime is 21726317. The next prime is 21726349. The reversal of 21726319 is 91362712.

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

It is not a de Polignac number, because 21726319 - 2¹ = 21726317 is a prime.

It is a super-2 number, since 2×21726319² = 944065874579522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 700849 = 21726319 / (2 + 1 + 7 + 2 + 6 + 3 + 1 + 9).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21726311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 350394 + ... + 350455.

It is an arithmetic number, because the mean of its divisors is an integer number (5606800).

Almost surely, 2^21726319 is an apocalyptic number.

21726319 is a deficient number, since it is larger than the sum of its proper divisors (700881).

21726319 is an equidigital number, since it uses as much as digits as its factorization.

21726319 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 700880.

The product of its digits is 4536, while the sum is 31.

The square root of 21726319 is about 4661.1499654055. The cubic root of 21726319 is about 279.0371648354.

The spelling of 21726319 in words is "twenty-one million, seven hundred twenty-six thousand, three hundred nineteen".