21115330331 has 4 divisors (see below), whose sum is σ = 21843445200. Its totient is φ = 20387215464.

The previous prime is 21115330319. The next prime is 21115330351. The reversal of 21115330331 is 13303351112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21115330331 is a prime.

It is a super-2 number, since 2×21115330331² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21115330297 and 21115330306.

It is not an unprimeable number, because it can be changed into a prime (21115330351) 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, 364057391 + ... + 364057448.

It is an arithmetic number, because the mean of its divisors is an integer number (5460861300).

Almost surely, 2^21115330331 is an apocalyptic number.

21115330331 is a deficient number, since it is larger than the sum of its proper divisors (728114869).

21115330331 is an equidigital number, since it uses as much as digits as its factorization.

21115330331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 728114868.

The product of its (nonzero) digits is 810, while the sum is 23.

Adding to 21115330331 its reverse (13303351112), we get a palindrome (34418681443).

The spelling of 21115330331 in words is "twenty-one billion, one hundred fifteen million, three hundred thirty thousand, three hundred thirty-one".