21840830 has 16 divisors (see below), whose sum is σ = 42887664. Its totient is φ = 7942080.

The previous prime is 21840829. The next prime is 21840851. The reversal of 21840830 is 3804812.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21840830.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 99167 + ... + 99386.

It is an arithmetic number, because the mean of its divisors is an integer number (2680479).

Almost surely, 2^21840830 is an apocalyptic number.

21840830 is a deficient number, since it is larger than the sum of its proper divisors (21046834).

21840830 is a wasteful number, since it uses less digits than its factorization.

21840830 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198571.

The product of its (nonzero) digits is 1536, while the sum is 26.

The square root of 21840830 is about 4673.4173791777. The cubic root of 21840830 is about 279.5265382938.

The spelling of 21840830 in words is "twenty-one million, eight hundred forty thousand, eight hundred thirty".