21812445 has 24 divisors (see below), whose sum is σ = 40033656. Its totient is φ = 10948608.

The previous prime is 21812429. The next prime is 21812447. The reversal of 21812445 is 54421812.

21812445 is a `hidden beast` number, since 218 + 1 + 2 + 445 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 10381284 + 11431161 = 3222^2 + 3381^2 .

It is not a de Polignac number, because 21812445 - 2⁴ = 21812429 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21812447) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13492 + ... + 15021.

It is an arithmetic number, because the mean of its divisors is an integer number (1668069).

Almost surely, 2^21812445 is an apocalyptic number.

It is an amenable number.

21812445 is a deficient number, since it is larger than the sum of its proper divisors (18221211).

21812445 is a wasteful number, since it uses less digits than its factorization.

21812445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28541 (or 28538 counting only the distinct ones).

The product of its digits is 2560, while the sum is 27.

The square root of 21812445 is about 4670.3795348986. The cubic root of 21812445 is about 279.4053920963.

The spelling of 21812445 in words is "twenty-one million, eight hundred twelve thousand, four hundred forty-five".