21318727 has 2 divisors, whose sum is σ = 21318728. Its totient is φ = 21318726.

The previous prime is 21318709. The next prime is 21318733. The reversal of 21318727 is 72781312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21318727 - 2⁷ = 21318599 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21318767) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10659363 + 10659364.

It is an arithmetic number, because the mean of its divisors is an integer number (10659364).

Almost surely, 2^21318727 is an apocalyptic number.

21318727 is a deficient number, since it is larger than the sum of its proper divisors (1).

21318727 is an equidigital number, since it uses as much as digits as its factorization.

21318727 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4704, while the sum is 31.

The square root of 21318727 is about 4617.2207008113. The cubic root of 21318727 is about 277.2811986271.

The spelling of 21318727 in words is "twenty-one million, three hundred eighteen thousand, seven hundred twenty-seven".