21015880100080 has 160 divisors (see below), whose sum is σ = 49834374681600. Its totient is φ = 8240329337856.

The previous prime is 21015880100071. The next prime is 21015880100081. The reversal of 21015880100080 is 8000108851012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21015880100081) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2073998694 + ... + 2074008826.

It is an arithmetic number, because the mean of its divisors is an integer number (311464841760).

Almost surely, 2^{21015880100080} is an apocalyptic number.

21015880100080 is a gapful number since it is divisible by the number (20) 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 21015880100080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24917187340800).

21015880100080 is an abundant number, since it is smaller than the sum of its proper divisors (28818494581520).

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

21015880100080 is a wasteful number, since it uses less digits than its factorization.

21015880100080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12071 (or 12065 counting only the distinct ones).

The product of its (nonzero) digits is 5120, while the sum is 34.

Adding to 21015880100080 its reverse (8000108851012), we get a palindrome (29015988951092).

The spelling of 21015880100080 in words is "twenty-one trillion, fifteen billion, eight hundred eighty million, one hundred thousand, eighty".