21985496181565 has 32 divisors (see below), whose sum is σ = 31285479663360. Its totient is φ = 14511938918400.

The previous prime is 21985496181557. The next prime is 21985496181569. The reversal of 21985496181565 is 56518169458912.

It is not a de Polignac number, because 21985496181565 - 2³ = 21985496181557 is a prime.

It is a Smith number, since the sum of its digits (70) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 21985496181494 and 21985496181503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21985496181569) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 32383956 + ... + 33055885.

It is an arithmetic number, because the mean of its divisors is an integer number (977671239480).

Almost surely, 2^{21985496181565} is an apocalyptic number.

It is an amenable number.

21985496181565 is a deficient number, since it is larger than the sum of its proper divisors (9299983481795).

21985496181565 is a wasteful number, since it uses less digits than its factorization.

21985496181565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65440213.

The product of its digits is 186624000, while the sum is 70.

The spelling of 21985496181565 in words is "twenty-one trillion, nine hundred eighty-five billion, four hundred ninety-six million, one hundred eighty-one thousand, five hundred sixty-five".