21100830 has 32 divisors (see below), whose sum is σ = 53308800. Its totient is φ = 5330592.

The previous prime is 21100823. The next prime is 21100853. The reversal of 21100830 is 3800112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 17940 + ... + 19079.

It is an arithmetic number, because the mean of its divisors is an integer number (1665900).

Almost surely, 2^21100830 is an apocalyptic number.

21100830 is an abundant number, since it is smaller than the sum of its proper divisors (32207970).

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

21100830 is a wasteful number, since it uses less digits than its factorization.

21100830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37048.

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 21100830 is about 4593.5639758253. The cubic root of 21100830 is about 276.3332720577. Note that the first 3 decimals are identical.

Adding to 21100830 its reverse (3800112), we get a palindrome (24900942).

The spelling of 21100830 in words is "twenty-one million, one hundred thousand, eight hundred thirty".