21678171648 has 80 divisors (see below), whose sum is σ = 66002323200. Its totient is φ = 6193760256.

The previous prime is 21678171607. The next prime is 21678171649. The reversal of 21678171648 is 84617187612.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21678171648.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21678171649) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 997348 + ... + 1018851.

It is an arithmetic number, because the mean of its divisors is an integer number (825029040).

Almost surely, 2^21678171648 is an apocalyptic number.

21678171648 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21678171648 is an abundant number, since it is smaller than the sum of its proper divisors (44324151552).

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

21678171648 is an equidigital number, since it uses as much as digits as its factorization.

21678171648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2016227 (or 2016211 counting only the distinct ones).

The product of its digits is 903168, while the sum is 51.

The spelling of 21678171648 in words is "twenty-one billion, six hundred seventy-eight million, one hundred seventy-one thousand, six hundred forty-eight".