21658319 has 2 divisors, whose sum is σ = 21658320. Its totient is φ = 21658318.

The previous prime is 21658277. The next prime is 21658321. The reversal of 21658319 is 91385612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21658319 - 2¹² = 21654223 is a prime.

It is a super-2 number, since 2×21658319² = 938165563811522, which contains 22 as substring.

Together with 21658321, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21658379) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10829159 + 10829160.

It is an arithmetic number, because the mean of its divisors is an integer number (10829160).

Almost surely, 2^21658319 is an apocalyptic number.

21658319 is a deficient number, since it is larger than the sum of its proper divisors (1).

21658319 is an equidigital number, since it uses as much as digits as its factorization.

21658319 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 35.

The square root of 21658319 is about 4653.8499116323. The cubic root of 21658319 is about 278.7457462803.

The spelling of 21658319 in words is "twenty-one million, six hundred fifty-eight thousand, three hundred nineteen".