21121144044 has 144 divisors (see below), whose sum is σ = 67351608576. Its totient is φ = 5063990400.

The previous prime is 21121144039. The next prime is 21121144049. The reversal of 21121144044 is 44044112112.

It is an interprime number because it is at equal distance from previous prime (21121144039) and next prime (21121144049).

It is a super-2 number, since 2×21121144044² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21121144049) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 41512 + ... + 209679.

It is an arithmetic number, because the mean of its divisors is an integer number (467719504).

Almost surely, 2^21121144044 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 21121144044, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33675804288).

21121144044 is an abundant number, since it is smaller than the sum of its proper divisors (46230464532).

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

21121144044 is a wasteful number, since it uses less digits than its factorization.

21121144044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 251236 (or 251227 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 24.

Adding to 21121144044 its reverse (44044112112), we get a palindrome (65165256156).

It can be divided in two parts, 211211 and 44044, that added together give a triangular number (255255 = T₇₁₄).

The spelling of 21121144044 in words is "twenty-one billion, one hundred twenty-one million, one hundred forty-four thousand, forty-four".