21585816594 has 12 divisors (see below), whose sum is σ = 46769269326. Its totient is φ = 7195272192.

The previous prime is 21585816583. The next prime is 21585816599. The reversal of 21585816594 is 49561858512.

21585816594 is a `hidden beast` number, since 2 + 1 + 5 + 8 + 581 + 6 + 59 + 4 = 666.

It can be written as a sum of positive squares in only one way, i.e., 21583429569 + 2387025 = 146913^2 + 1545^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21585816594.

It is not an unprimeable number, because it can be changed into a prime (21585816599) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 599605999 + ... + 599606034.

Almost surely, 2^21585816594 is an apocalyptic number.

21585816594 is an abundant number, since it is smaller than the sum of its proper divisors (25183452732).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21585816594 is a wasteful number, since it uses less digits than its factorization.

21585816594 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1199212041 (or 1199212038 counting only the distinct ones).

The product of its digits is 3456000, while the sum is 54.

The spelling of 21585816594 in words is "twenty-one billion, five hundred eighty-five million, eight hundred sixteen thousand, five hundred ninety-four".