21744745 has 16 divisors (see below), whose sum is σ = 28952640. Its totient is φ = 15544000.

The previous prime is 21744739. The next prime is 21744757. The reversal of 21744745 is 54744712.

It is a happy number.

It is not a de Polignac number, because 21744745 - 2⁷ = 21744617 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21744745.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 106 + ... + 6595.

It is an arithmetic number, because the mean of its divisors is an integer number (1809540).

Almost surely, 2^21744745 is an apocalyptic number.

It is an amenable number.

21744745 is a deficient number, since it is larger than the sum of its proper divisors (7207895).

21744745 is a wasteful number, since it uses less digits than its factorization.

21744745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6776.

The product of its digits is 31360, while the sum is 34.

The square root of 21744745 is about 4663.1260973729. The cubic root of 21744745 is about 279.1160259620.

The spelling of 21744745 in words is "twenty-one million, seven hundred forty-four thousand, seven hundred forty-five".