21900830 has 64 divisors (see below), whose sum is σ = 47996928. Its totient is φ = 7032960.

The previous prime is 21900821. The next prime is 21900833. The reversal of 21900830 is 3800912.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21900796 and 21900805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21900833) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 98099 + ... + 98321.

It is an arithmetic number, because the mean of its divisors is an integer number (749952).

Almost surely, 2^21900830 is an apocalyptic number.

21900830 is an abundant number, since it is smaller than the sum of its proper divisors (26096098).

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

21900830 is a wasteful number, since it uses less digits than its factorization.

21900830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 21900830 is about 4679.8322619513. The cubic root of 21900830 is about 279.7822712136.

The spelling of 21900830 in words is "twenty-one million, nine hundred thousand, eight hundred thirty".