21191407844 has 12 divisors (see below), whose sum is σ = 37086499884. Its totient is φ = 10595265024.

The previous prime is 21191407841. The next prime is 21191407891. The reversal of 21191407844 is 44870419112.

It can be written as a sum of positive squares in 2 ways, for example, as 6446162944 + 14745244900 = 80288^2 + 121430^2 .

It is not an unprimeable number, because it can be changed into a prime (21191407841) 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 3 ways as a sum of consecutive naturals, for example, 14552 + ... + 206384.

It is an arithmetic number, because the mean of its divisors is an integer number (3090541657).

Almost surely, 2^21191407844 is an apocalyptic number.

It is an amenable number.

21191407844 is a deficient number, since it is larger than the sum of its proper divisors (15895092040).

21191407844 is a wasteful number, since it uses less digits than its factorization.

21191407844 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 219454 (or 219452 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 41.

The spelling of 21191407844 in words is "twenty-one billion, one hundred ninety-one million, four hundred seven thousand, eight hundred forty-four".