21013111044 has 144 divisors (see below), whose sum is σ = 57269459520. Its totient is φ = 6728883840.

The previous prime is 21013110997. The next prime is 21013111051. The reversal of 21013111044 is 44011131012.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5945902 + ... + 5949434.

It is an arithmetic number, because the mean of its divisors is an integer number (397704580).

Almost surely, 2^21013111044 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 21013111044, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28634729760).

21013111044 is an abundant number, since it is smaller than the sum of its proper divisors (36256348476).

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

21013111044 is a wasteful number, since it uses less digits than its factorization.

21013111044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3792 (or 3778 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

Adding to 21013111044 its reverse (44011131012), we get a palindrome (65024242056).

The spelling of 21013111044 in words is "twenty-one billion, thirteen million, one hundred eleven thousand, forty-four".