21861859791 has 16 divisors (see below), whose sum is σ = 29777094144. Its totient is φ = 14260761024.

The previous prime is 21861859777. The next prime is 21861859807. The reversal of 21861859791 is 19795816812.

It is not a de Polignac number, because 21861859791 - 2⁶ = 21861859727 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21861859741) 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, 587836 + ... + 623918.

It is an arithmetic number, because the mean of its divisors is an integer number (1861068384).

Almost surely, 2^21861859791 is an apocalyptic number.

21861859791 is a deficient number, since it is larger than the sum of its proper divisors (7915234353).

21861859791 is a wasteful number, since it uses less digits than its factorization.

21861859791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40430.

The product of its digits is 2177280, while the sum is 57.

The spelling of 21861859791 in words is "twenty-one billion, eight hundred sixty-one million, eight hundred fifty-nine thousand, seven hundred ninety-one".