21779473 has 2 divisors, whose sum is σ = 21779474. Its totient is φ = 21779472.

The previous prime is 21779447. The next prime is 21779497. The reversal of 21779473 is 37497712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20638849 + 1140624 = 4543^2 + 1068^2 .

It is a cyclic number.

It is not a de Polignac number, because 21779473 - 2¹⁷ = 21648401 is a prime.

It is not a weakly prime, because it can be changed into another prime (21779423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10889736 + 10889737.

It is an arithmetic number, because the mean of its divisors is an integer number (10889737).

Almost surely, 2^21779473 is an apocalyptic number.

It is an amenable number.

21779473 is a deficient number, since it is larger than the sum of its proper divisors (1).

21779473 is an equidigital number, since it uses as much as digits as its factorization.

21779473 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 74088, while the sum is 40.

The square root of 21779473 is about 4666.8482940846. The cubic root of 21779473 is about 279.2645367201.

The spelling of 21779473 in words is "twenty-one million, seven hundred seventy-nine thousand, four hundred seventy-three".