21406279 has 2 divisors, whose sum is σ = 21406280. Its totient is φ = 21406278.

The previous prime is 21406271. The next prime is 21406339. The reversal of 21406279 is 97260412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21406279 - 2³ = 21406271 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21406279.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21406271) 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, 10703139 + 10703140.

It is an arithmetic number, because the mean of its divisors is an integer number (10703140).

Almost surely, 2^21406279 is an apocalyptic number.

21406279 is a deficient number, since it is larger than the sum of its proper divisors (1).

21406279 is an equidigital number, since it uses as much as digits as its factorization.

21406279 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6048, while the sum is 31.

The square root of 21406279 is about 4626.6920148201. The cubic root of 21406279 is about 277.6602607553.

The spelling of 21406279 in words is "twenty-one million, four hundred six thousand, two hundred seventy-nine".