21104251115 has 4 divisors (see below), whose sum is σ = 25325101344. Its totient is φ = 16883400888.

The previous prime is 21104251111. The next prime is 21104251117. The reversal of 21104251115 is 51115240112.

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 21104251115 - 2² = 21104251111 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21104251111) 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, 2110425107 + ... + 2110425116.

It is an arithmetic number, because the mean of its divisors is an integer number (6331275336).

Almost surely, 2^21104251115 is an apocalyptic number.

21104251115 is a deficient number, since it is larger than the sum of its proper divisors (4220850229).

21104251115 is an equidigital number, since it uses as much as digits as its factorization.

21104251115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4220850228.

The product of its (nonzero) digits is 400, while the sum is 23.

Adding to 21104251115 its reverse (51115240112), we get a palindrome (72219491227).

The spelling of 21104251115 in words is "twenty-one billion, one hundred four million, two hundred fifty-one thousand, one hundred fifteen".