21801128076 has 384 divisors, whose sum is σ = 72414003200. Its totient is φ = 5517538560.

The previous prime is 21801128033. The next prime is 21801128087. The reversal of 21801128076 is 67082110812.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21801128076.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 49660665 + ... + 49661103.

Almost surely, 2^21801128076 is an apocalyptic number.

21801128076 is a gapful number since it is divisible by the number (26) 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 21801128076, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36207001600).

21801128076 is an abundant number, since it is smaller than the sum of its proper divisors (50612875124).

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

21801128076 is a wasteful number, since it uses less digits than its factorization.

21801128076 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 666 (or 658 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 36.

Adding to 21801128076 its reverse (67082110812), we get a palindrome (88883238888).

It can be divided in two parts, 2180 and 1128076, that added together give a triangular number (1130256 = T₁₅₀₃).

The spelling of 21801128076 in words is "twenty-one billion, eight hundred one million, one hundred twenty-eight thousand, seventy-six".