21859042591 has 4 divisors (see below), whose sum is σ = 21863008800. Its totient is φ = 21855076384.

The previous prime is 21859042529. The next prime is 21859042607. The reversal of 21859042591 is 19524095812.

It is a happy number.

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 21859042591 - 2²⁹ = 21322171679 is a prime.

It is a super-3 number, since 3×21859042591³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21859042501) 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, 1974826 + ... + 1985863.

It is an arithmetic number, because the mean of its divisors is an integer number (5465752200).

Almost surely, 2^21859042591 is an apocalyptic number.

21859042591 is a deficient number, since it is larger than the sum of its proper divisors (3966209).

21859042591 is an equidigital number, since it uses as much as digits as its factorization.

21859042591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3966208.

The product of its (nonzero) digits is 259200, while the sum is 46.

The spelling of 21859042591 in words is "twenty-one billion, eight hundred fifty-nine million, forty-two thousand, five hundred ninety-one".