21105799 has 16 divisors (see below), whose sum is σ = 25472160. Its totient is φ = 17228160.

The previous prime is 21105781. The next prime is 21105811. The reversal of 21105799 is 99750112.

It is a cyclic number.

It is not a de Polignac number, because 21105799 - 2⁵ = 21105767 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105709) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3297 + ... + 7285.

It is an arithmetic number, because the mean of its divisors is an integer number (1592010).

Almost surely, 2^21105799 is an apocalyptic number.

21105799 is a deficient number, since it is larger than the sum of its proper divisors (4366361).

21105799 is a wasteful number, since it uses less digits than its factorization.

21105799 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4050.

The product of its (nonzero) digits is 5670, while the sum is 34.

The square root of 21105799 is about 4594.1048094270. The cubic root of 21105799 is about 276.3549614456.

It can be divided in two parts, 21105 and 799, that added together give a square (21904 = 148²).

The spelling of 21105799 in words is "twenty-one million, one hundred five thousand, seven hundred ninety-nine".