21375859 has 4 divisors (see below), whose sum is σ = 21873016. Its totient is φ = 20878704.

The previous prime is 21375853. The next prime is 21375889. The reversal of 21375859 is 95857312.

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 21375859 - 2¹⁷ = 21244787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21375853) 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 3 ways as a sum of consecutive naturals, for example, 248514 + ... + 248599.

It is an arithmetic number, because the mean of its divisors is an integer number (5468254).

Almost surely, 2^21375859 is an apocalyptic number.

21375859 is a deficient number, since it is larger than the sum of its proper divisors (497157).

21375859 is an equidigital number, since it uses as much as digits as its factorization.

21375859 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 497156.

The product of its digits is 75600, while the sum is 40.

The square root of 21375859 is about 4623.4034000939. The cubic root of 21375859 is about 277.5286727400.

The spelling of 21375859 in words is "twenty-one million, three hundred seventy-five thousand, eight hundred fifty-nine".