21744779 has 6 divisors (see below), whose sum is σ = 25295004. Its totient is φ = 18638340.

The previous prime is 21744763. The next prime is 21744803. The reversal of 21744779 is 97744712.

It is not a de Polignac number, because 21744779 - 2⁴ = 21744763 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21744739) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 221837 + ... + 221934.

It is an arithmetic number, because the mean of its divisors is an integer number (4215834).

Almost surely, 2^21744779 is an apocalyptic number.

21744779 is a deficient number, since it is larger than the sum of its proper divisors (3550225).

21744779 is an equidigital number, since it uses as much as digits as its factorization.

21744779 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 443785 (or 443778 counting only the distinct ones).

The product of its digits is 98784, while the sum is 41.

The square root of 21744779 is about 4663.1297429945. The cubic root of 21744779 is about 279.1161714368.

The spelling of 21744779 in words is "twenty-one million, seven hundred forty-four thousand, seven hundred seventy-nine".