21317479 has 2 divisors, whose sum is σ = 21317480. Its totient is φ = 21317478.

The previous prime is 21317447. The next prime is 21317509. The reversal of 21317479 is 97471312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21317479 - 2⁵ = 21317447 is a prime.

It is equal to p_1348774 and since 21317479 and 1348774 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21317419) 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, 10658739 + 10658740.

It is an arithmetic number, because the mean of its divisors is an integer number (10658740).

Almost surely, 2^21317479 is an apocalyptic number.

21317479 is a deficient number, since it is larger than the sum of its proper divisors (1).

21317479 is an equidigital number, since it uses as much as digits as its factorization.

21317479 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10584, while the sum is 34.

The square root of 21317479 is about 4617.0855525970. The cubic root of 21317479 is about 277.2757878336.

The spelling of 21317479 in words is "twenty-one million, three hundred seventeen thousand, four hundred seventy-nine".