21849745 has 4 divisors (see below), whose sum is σ = 26219700. Its totient is φ = 17479792.

The previous prime is 21849739. The next prime is 21849749. The reversal of 21849745 is 54794812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17114769 + 4734976 = 4137^2 + 2176^2 .

It is a cyclic number.

It is not a de Polignac number, because 21849745 - 2¹⁹ = 21325457 is a prime.

It is a super-2 number, since 2×21849745² = 954822713130050, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21849698 and 21849707.

It is not an unprimeable number, because it can be changed into a prime (21849749) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2184970 + ... + 2184979.

It is an arithmetic number, because the mean of its divisors is an integer number (6554925).

Almost surely, 2^21849745 is an apocalyptic number.

It is an amenable number.

21849745 is a deficient number, since it is larger than the sum of its proper divisors (4369955).

21849745 is an equidigital number, since it uses as much as digits as its factorization.

21849745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4369954.

The product of its digits is 80640, while the sum is 40.

The square root of 21849745 is about 4674.3710806910. The cubic root of 21849745 is about 279.5645655438.

The spelling of 21849745 in words is "twenty-one million, eight hundred forty-nine thousand, seven hundred forty-five".