21597168861 has 16 divisors (see below), whose sum is σ = 32081600320. Its totient is φ = 14359505040.

The previous prime is 21597168847. The next prime is 21597168871. The reversal of 21597168861 is 16886179512.

It is a happy number.

It is not a de Polignac number, because 21597168861 - 2¹⁸ = 21596906717 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21597168798 and 21597168807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21597168821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1062175 + ... + 1082316.

It is an arithmetic number, because the mean of its divisors is an integer number (2005100020).

Almost surely, 2^21597168861 is an apocalyptic number.

It is an amenable number.

21597168861 is a deficient number, since it is larger than the sum of its proper divisors (10484431459).

21597168861 is a wasteful number, since it uses less digits than its factorization.

21597168861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2144873 (or 2144867 counting only the distinct ones).

The product of its digits is 1451520, while the sum is 54.

The spelling of 21597168861 in words is "twenty-one billion, five hundred ninety-seven million, one hundred sixty-eight thousand, eight hundred sixty-one".