21218759 has 2 divisors, whose sum is σ = 21218760. Its totient is φ = 21218758.

The previous prime is 21218741. The next prime is 21218777. The reversal of 21218759 is 95781212.

It is a balanced prime because it is at equal distance from previous prime (21218741) and next prime (21218777).

It is a cyclic number.

It is not a de Polignac number, because 21218759 - 2⁸ = 21218503 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21218059) 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, 10609379 + 10609380.

It is an arithmetic number, because the mean of its divisors is an integer number (10609380).

Almost surely, 2^21218759 is an apocalyptic number.

21218759 is a deficient number, since it is larger than the sum of its proper divisors (1).

21218759 is an equidigital number, since it uses as much as digits as its factorization.

21218759 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10080, while the sum is 35.

The square root of 21218759 is about 4606.3824200776. The cubic root of 21218759 is about 276.8471094306.

The spelling of 21218759 in words is "twenty-one million, two hundred eighteen thousand, seven hundred fifty-nine".