21143818 has 24 divisors (see below), whose sum is σ = 34051212. Its totient is φ = 9844224.

The previous prime is 21143807. The next prime is 21143839. The reversal of 21143818 is 81834112.

It can be written as a sum of positive squares in 6 ways, for example, as 11202409 + 9941409 = 3347^2 + 3153^2 .

It is a super-2 number, since 2×21143818² = 894122079234248, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 90630 + ... + 90862.

Almost surely, 2^21143818 is an apocalyptic number.

21143818 is a deficient number, since it is larger than the sum of its proper divisors (12907394).

21143818 is a wasteful number, since it uses less digits than its factorization.

21143818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 426 (or 409 counting only the distinct ones).

The product of its digits is 1536, while the sum is 28.

The square root of 21143818 is about 4598.2407505480. The cubic root of 21143818 is about 276.5207995454.

The spelling of 21143818 in words is "twenty-one million, one hundred forty-three thousand, eight hundred eighteen".