21512044111 has 4 divisors (see below), whose sum is σ = 21568211712. Its totient is φ = 21455876512.

The previous prime is 21512044063. The next prime is 21512044133. The reversal of 21512044111 is 11144021512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21512044111 - 2⁷ = 21512043983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21512044181) 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, 28083226 + ... + 28083991.

It is an arithmetic number, because the mean of its divisors is an integer number (5392052928).

Almost surely, 2^21512044111 is an apocalyptic number.

21512044111 is a deficient number, since it is larger than the sum of its proper divisors (56167601).

21512044111 is an equidigital number, since it uses as much as digits as its factorization.

21512044111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56167600.

The product of its (nonzero) digits is 320, while the sum is 22.

Adding to 21512044111 its reverse (11144021512), we get a palindrome (32656065623).

The spelling of 21512044111 in words is "twenty-one billion, five hundred twelve million, forty-four thousand, one hundred eleven".