21497591799 has 12 divisors (see below), whose sum is σ = 31150037256. Its totient is φ = 14286515472.

The previous prime is 21497591779. The next prime is 21497591821. The reversal of 21497591799 is 99719579412.

It is a happy number.

21497591799 is a `hidden beast` number, since 2 + 1 + 497 + 59 + 1 + 7 + 99 = 666.

It is not a de Polignac number, because 21497591799 - 2¹³ = 21497583607 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21497591719) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3764689 + ... + 3770394.

It is an arithmetic number, because the mean of its divisors is an integer number (2595836438).

Almost surely, 2^21497591799 is an apocalyptic number.

21497591799 is a deficient number, since it is larger than the sum of its proper divisors (9652445457).

21497591799 is a wasteful number, since it uses less digits than its factorization.

21497591799 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7535406 (or 7535403 counting only the distinct ones).

The product of its digits is 12859560, while the sum is 63.

The spelling of 21497591799 in words is "twenty-one billion, four hundred ninety-seven million, five hundred ninety-one thousand, seven hundred ninety-nine".