21813445 has 4 divisors (see below), whose sum is σ = 26176140. Its totient is φ = 17450752.

The previous prime is 21813433. The next prime is 21813469. The reversal of 21813445 is 54431812.

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 11840481 + 9972964 = 3441^2 + 3158^2 .

It is a cyclic number.

It is not a de Polignac number, because 21813445 - 2¹¹ = 21811397 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, 2181340 + ... + 2181349.

It is an arithmetic number, because the mean of its divisors is an integer number (6544035).

Almost surely, 2^21813445 is an apocalyptic number.

It is an amenable number.

21813445 is a deficient number, since it is larger than the sum of its proper divisors (4362695).

21813445 is an equidigital number, since it uses as much as digits as its factorization.

21813445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4362694.

The product of its digits is 3840, while the sum is 28.

The square root of 21813445 is about 4670.4865913521. The cubic root of 21813445 is about 279.4096618472.

The spelling of 21813445 in words is "twenty-one million, eight hundred thirteen thousand, four hundred forty-five".