21318379 has 2 divisors, whose sum is σ = 21318380. Its totient is φ = 21318378.

The previous prime is 21318377. The next prime is 21318397. The reversal of 21318379 is 97381312.

Together with next prime (21318397) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21318379 - 2¹ = 21318377 is a prime.

Together with 21318377, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21318377) 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 as a sum of consecutive naturals, namely, 10659189 + 10659190.

It is an arithmetic number, because the mean of its divisors is an integer number (10659190).

Almost surely, 2^21318379 is an apocalyptic number.

21318379 is a deficient number, since it is larger than the sum of its proper divisors (1).

21318379 is an equidigital number, since it uses as much as digits as its factorization.

21318379 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9072, while the sum is 34.

The square root of 21318379 is about 4617.1830156493. The cubic root of 21318379 is about 277.2796898694.

The spelling of 21318379 in words is "twenty-one million, three hundred eighteen thousand, three hundred seventy-nine".