21745859 has 4 divisors (see below), whose sum is σ = 21807816. Its totient is φ = 21683904.

The previous prime is 21745799. The next prime is 21745901. The reversal of 21745859 is 95854712.

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 21745859 - 2²⁰ = 20697283 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21744859) 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, 30449 + ... + 31154.

It is an arithmetic number, because the mean of its divisors is an integer number (5451954).

Almost surely, 2^21745859 is an apocalyptic number.

21745859 is a deficient number, since it is larger than the sum of its proper divisors (61957).

21745859 is an equidigital number, since it uses as much as digits as its factorization.

21745859 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61956.

The product of its digits is 100800, while the sum is 41.

The square root of 21745859 is about 4663.2455436102. The cubic root of 21745859 is about 279.1207923235.

The spelling of 21745859 in words is "twenty-one million, seven hundred forty-five thousand, eight hundred fifty-nine".