21456829 has 2 divisors, whose sum is σ = 21456830. Its totient is φ = 21456828.

The previous prime is 21456797. The next prime is 21456859. The reversal of 21456829 is 92865412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14707225 + 6749604 = 3835^2 + 2598^2 .

It is a cyclic number.

It is not a de Polignac number, because 21456829 - 2⁵ = 21456797 is a prime.

It is a nialpdrome in base 9.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21456859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10728414 + 10728415.

It is an arithmetic number, because the mean of its divisors is an integer number (10728415).

Almost surely, 2^21456829 is an apocalyptic number.

It is an amenable number.

21456829 is a deficient number, since it is larger than the sum of its proper divisors (1).

21456829 is an equidigital number, since it uses as much as digits as its factorization.

21456829 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34560, while the sum is 37.

The square root of 21456829 is about 4632.1516598661. The cubic root of 21456829 is about 277.8786498301.

The spelling of 21456829 in words is "twenty-one million, four hundred fifty-six thousand, eight hundred twenty-nine".