21766638313728 has 864 divisors, whose sum is σ = 80787423854592. Its totient is φ = 5472114278400.

The previous prime is 21766638313727. The next prime is 21766638313801. The reversal of 21766638313728 is 82731383666712.

It is a Cunningham number, because it is equal to 4665473²-1.

It is a super-2 number, since 2×21766638313728² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

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

It is not an unprimeable number, because it can be changed into a prime (21766638313727) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 923751675 + ... + 923775237.

Almost surely, 2^{21766638313728} is an apocalyptic number.

21766638313728 is a gapful number since it is divisible by the number (28) 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 21766638313728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40393711927296).

21766638313728 is an abundant number, since it is smaller than the sum of its proper divisors (59020785540864).

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

21766638313728 is a wasteful number, since it uses less digits than its factorization.

21766638313728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23771 (or 23754 counting only the distinct ones).

The product of its digits is 73156608, while the sum is 63.

The spelling of 21766638313728 in words is "twenty-one trillion, seven hundred sixty-six billion, six hundred thirty-eight million, three hundred thirteen thousand, seven hundred twenty-eight".