21129886969 has 4 divisors (see below), whose sum is σ = 21162245796. Its totient is φ = 21097528144.

The previous prime is 21129886937. The next prime is 21129887017. The reversal of 21129886969 is 96968892112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 2392383744 + 18737503225 = 48912^2 + 136885^2 .

It is a cyclic number.

It is not a de Polignac number, because 21129886969 - 2⁵ = 21129886937 is a prime.

It is a super-2 number, since 2×21129886969² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21129886469) 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, 16178434 + ... + 16179739.

It is an arithmetic number, because the mean of its divisors is an integer number (5290561449).

Almost surely, 2^21129886969 is an apocalyptic number.

It is an amenable number.

21129886969 is a deficient number, since it is larger than the sum of its proper divisors (32358827).

21129886969 is an equidigital number, since it uses as much as digits as its factorization.

21129886969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32358826.

The product of its digits is 6718464, while the sum is 61.

The spelling of 21129886969 in words is "twenty-one billion, one hundred twenty-nine million, eight hundred eighty-six thousand, nine hundred sixty-nine".