21790859 has 4 divisors (see below), whose sum is σ = 21884616. Its totient is φ = 21697104.

The previous prime is 21790843. The next prime is 21790921. The reversal of 21790859 is 95809712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21790859 - 2⁴ = 21790843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21790159) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46529 + ... + 46994.

It is an arithmetic number, because the mean of its divisors is an integer number (5471154).

Almost surely, 2^21790859 is an apocalyptic number.

21790859 is a deficient number, since it is larger than the sum of its proper divisors (93757).

21790859 is an equidigital number, since it uses as much as digits as its factorization.

21790859 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93756.

The product of its (nonzero) digits is 45360, while the sum is 41.

The square root of 21790859 is about 4668.0680157855. The cubic root of 21790859 is about 279.3131934236.

The spelling of 21790859 in words is "twenty-one million, seven hundred ninety thousand, eight hundred fifty-nine".