21511644331136 has 128 divisors (see below), whose sum is σ = 46128943912320. Its totient is φ = 9956505600000.

The previous prime is 21511644331129. The next prime is 21511644331147. The reversal of 21511644331136 is 63113344611512.

It is a tau number, because it is divible by the number of its divisors (128).

It is a hoax number, since the sum of its digits (41) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21511644331093 and 21511644331102.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32862071 + ... + 33510281.

It is an arithmetic number, because the mean of its divisors is an integer number (360382374315).

Almost surely, 2^{21511644331136} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21511644331136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23064471956160).

21511644331136 is an abundant number, since it is smaller than the sum of its proper divisors (24617299581184).

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

21511644331136 is a wasteful number, since it uses less digits than its factorization.

21511644331136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 648494 (or 648482 counting only the distinct ones).

The product of its digits is 155520, while the sum is 41.

Adding to 21511644331136 its reverse (63113344611512), we get a palindrome (84624988942648).

The spelling of 21511644331136 in words is "twenty-one trillion, five hundred eleven billion, six hundred forty-four million, three hundred thirty-one thousand, one hundred thirty-six".