21818373 has 4 divisors (see below), whose sum is σ = 29091168. Its totient is φ = 14545580.

The previous prime is 21818359. The next prime is 21818393. The reversal of 21818373 is 37381812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21818373 - 2⁶ = 21818309 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21818393) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3636393 + ... + 3636398.

It is an arithmetic number, because the mean of its divisors is an integer number (7272792).

Almost surely, 2^21818373 is an apocalyptic number.

It is an amenable number.

21818373 is a deficient number, since it is larger than the sum of its proper divisors (7272795).

21818373 is an equidigital number, since it uses as much as digits as its factorization.

21818373 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7272794.

The product of its digits is 8064, while the sum is 33.

The square root of 21818373 is about 4671.0141297153. The cubic root of 21818373 is about 279.4307012740.

The spelling of 21818373 in words is "twenty-one million, eight hundred eighteen thousand, three hundred seventy-three".