21608378660775 has 24 divisors (see below), whose sum is σ = 36691416310864. Its totient is φ = 11212996492800.

The previous prime is 21608378660773. The next prime is 21608378660777. The reversal of 21608378660775 is 57706687380612.

It is an interprime number because it is at equal distance from previous prime (21608378660773) and next prime (21608378660777).

It is not a de Polignac number, because 21608378660775 - 2¹ = 21608378660773 is a prime.

It is a Smith number, since the sum of its digits (66) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21608378660773) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3893398786 + ... + 3893404335.

Almost surely, 2^{21608378660775} is an apocalyptic number.

21608378660775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21608378660775 is a deficient number, since it is larger than the sum of its proper divisors (15083037650089).

21608378660775 is a wasteful number, since it uses less digits than its factorization.

21608378660775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7786803171 (or 7786803166 counting only the distinct ones).

The product of its (nonzero) digits is 142248960, while the sum is 66.

The spelling of 21608378660775 in words is "twenty-one trillion, six hundred eight billion, three hundred seventy-eight million, six hundred sixty thousand, seven hundred seventy-five".