21818394 has 24 divisors (see below), whose sum is σ = 50910132. Its totient is φ = 6713280.

The previous prime is 21818393. The next prime is 21818399. The reversal of 21818394 is 49381812.

It can be written as a sum of positive squares in 2 ways, for example, as 21762225 + 56169 = 4665^2 + 237^2 .

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

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 46387 + ... + 46854.

Almost surely, 2^21818394 is an apocalyptic number.

21818394 is an abundant number, since it is smaller than the sum of its proper divisors (29091738).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21818394 is a wasteful number, since it uses less digits than its factorization.

21818394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93262 (or 93259 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 21818394 is about 4671.0163776206. The cubic root of 21818394 is about 279.4307909238.

The spelling of 21818394 in words is "twenty-one million, eight hundred eighteen thousand, three hundred ninety-four".