21687319 has 8 divisors (see below), whose sum is σ = 22487472. Its totient is φ = 20900160.

The previous prime is 21687307. The next prime is 21687329. The reversal of 21687319 is 91378612.

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

It is not a de Polignac number, because 21687319 - 2⁵ = 21687287 is a prime.

It is a super-2 number, since 2×21687319² = 940679610815522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21687329) 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 7 ways as a sum of consecutive naturals, for example, 217 + ... + 6589.

It is an arithmetic number, because the mean of its divisors is an integer number (2810934).

Almost surely, 2^21687319 is an apocalyptic number.

21687319 is a deficient number, since it is larger than the sum of its proper divisors (800153).

21687319 is an equidigital number, since it uses as much as digits as its factorization.

21687319 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6497.

The product of its digits is 18144, while the sum is 37.

The square root of 21687319 is about 4656.9645693305. The cubic root of 21687319 is about 278.8701022132.

The spelling of 21687319 in words is "twenty-one million, six hundred eighty-seven thousand, three hundred nineteen".