21198764664 has 640 divisors, whose sum is σ = 79453440000. Its totient is φ = 5114430720.

The previous prime is 21198764651. The next prime is 21198764693. The reversal of 21198764664 is 46646789112.

21198764664 is a `hidden beast` number, since 21 + 1 + 98 + 76 + 466 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

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 21198764664.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 55933227 + ... + 55933605.

It is an arithmetic number, because the mean of its divisors is an integer number (124146000).

Almost surely, 2^21198764664 is an apocalyptic number.

21198764664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21198764664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39726720000).

21198764664 is an abundant number, since it is smaller than the sum of its proper divisors (58254675336).

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

21198764664 is a wasteful number, since it uses less digits than its factorization.

21198764664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 493 (or 480 counting only the distinct ones).

The product of its digits is 3483648, while the sum is 54.

The spelling of 21198764664 in words is "twenty-one billion, one hundred ninety-eight million, seven hundred sixty-four thousand, six hundred sixty-four".