21804779 has 2 divisors, whose sum is σ = 21804780. Its totient is φ = 21804778.

The previous prime is 21804737. The next prime is 21804793. The reversal of 21804779 is 97740812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21804779 - 2¹² = 21800683 is a prime.

It is not a weakly prime, because it can be changed into another prime (21804719) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10902389 + 10902390.

It is an arithmetic number, because the mean of its divisors is an integer number (10902390).

Almost surely, 2^21804779 is an apocalyptic number.

21804779 is a deficient number, since it is larger than the sum of its proper divisors (1).

21804779 is an equidigital number, since it uses as much as digits as its factorization.

21804779 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28224, while the sum is 38.

The square root of 21804779 is about 4669.5587585981. The cubic root of 21804779 is about 279.3726558500.

The spelling of 21804779 in words is "twenty-one million, eight hundred four thousand, seven hundred seventy-nine".