21100839 has 8 divisors (see below), whose sum is σ = 28307712. Its totient is φ = 13980600.

The previous prime is 21100823. The next prime is 21100853. The reversal of 21100839 is 93800112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21100839 - 2⁴ = 21100823 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100939) 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 7 ways as a sum of consecutive naturals, for example, 21087 + ... + 22064.

It is an arithmetic number, because the mean of its divisors is an integer number (3538464).

Almost surely, 2^21100839 is an apocalyptic number.

21100839 is a deficient number, since it is larger than the sum of its proper divisors (7206873).

21100839 is a wasteful number, since it uses less digits than its factorization.

21100839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43317.

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 21100839 is about 4593.5649554567. The cubic root of 21100839 is about 276.3333113453. Note that the first 4 decimals are identical.

The spelling of 21100839 in words is "twenty-one million, one hundred thousand, eight hundred thirty-nine".