21764245 has 4 divisors (see below), whose sum is σ = 26117100. Its totient is φ = 17411392.

The previous prime is 21764227. The next prime is 21764257. The reversal of 21764245 is 54246712.

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 9771876 + 11992369 = 3126^2 + 3463^2 .

It is a cyclic number.

It is not a de Polignac number, because 21764245 - 2¹¹ = 21762197 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2176420 + ... + 2176429.

It is an arithmetic number, because the mean of its divisors is an integer number (6529275).

Almost surely, 2^21764245 is an apocalyptic number.

It is an amenable number.

21764245 is a deficient number, since it is larger than the sum of its proper divisors (4352855).

21764245 is an equidigital number, since it uses as much as digits as its factorization.

21764245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4352854.

The product of its digits is 13440, while the sum is 31.

The square root of 21764245 is about 4665.2165008711. The cubic root of 21764245 is about 279.1994351773.

The spelling of 21764245 in words is "twenty-one million, seven hundred sixty-four thousand, two hundred forty-five".