21123444444 has 48 divisors (see below), whose sum is σ = 53204497920. Its totient is φ = 6502767040.

The previous prime is 21123444443. The next prime is 21123444457. The reversal of 21123444444 is 44444432112.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123444443) 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 15 ways as a sum of consecutive naturals, for example, 1311552 + ... + 1327559.

It is an arithmetic number, because the mean of its divisors is an integer number (1108427040).

Almost surely, 2^21123444444 is an apocalyptic number.

It is an amenable number.

21123444444 is an abundant number, since it is smaller than the sum of its proper divisors (32081053476).

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

21123444444 is a wasteful number, since it uses less digits than its factorization.

21123444444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2639170 (or 2639168 counting only the distinct ones).

The product of its digits is 49152, while the sum is 33.

Adding to 21123444444 its reverse (44444432112), we get a palindrome (65567876556).

The spelling of 21123444444 in words is "twenty-one billion, one hundred twenty-three million, four hundred forty-four thousand, four hundred forty-four".