21115344401 has 4 divisors (see below), whose sum is σ = 21115646772. Its totient is φ = 21115042032.

The previous prime is 21115344391. The next prime is 21115344449. The reversal of 21115344401 is 10444351112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 14732133376 + 6383211025 = 121376^2 + 79895^2 .

It is a cyclic number.

It is not a de Polignac number, because 21115344401 - 2³⁰ = 20041602577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21115344451) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12995 + ... + 205911.

It is an arithmetic number, because the mean of its divisors is an integer number (5278911693).

Almost surely, 2^21115344401 is an apocalyptic number.

It is an amenable number.

21115344401 is a deficient number, since it is larger than the sum of its proper divisors (302371).

21115344401 is a wasteful number, since it uses less digits than its factorization.

21115344401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 302370.

The product of its (nonzero) digits is 1920, while the sum is 26.

Adding to 21115344401 its reverse (10444351112), we get a palindrome (31559695513).

The spelling of 21115344401 in words is "twenty-one billion, one hundred fifteen million, three hundred forty-four thousand, four hundred one".