21056459 has 2 divisors, whose sum is σ = 21056460. Its totient is φ = 21056458.

The previous prime is 21056447. The next prime is 21056479. The reversal of 21056459 is 95465012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21056459 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21056479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10528229 + 10528230.

It is an arithmetic number, because the mean of its divisors is an integer number (10528230).

Almost surely, 2^21056459 is an apocalyptic number.

21056459 is a deficient number, since it is larger than the sum of its proper divisors (1).

21056459 is an equidigital number, since it uses as much as digits as its factorization.

21056459 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10800, while the sum is 32.

The square root of 21056459 is about 4588.7317419958. The cubic root of 21056459 is about 276.1394441692.

The spelling of 21056459 in words is "twenty-one million, fifty-six thousand, four hundred fifty-nine".