21911631818 has 8 divisors (see below), whose sum is σ = 33126246912. Its totient is φ = 10869549516.

The previous prime is 21911631799. The next prime is 21911631883. The reversal of 21911631818 is 81813611912.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43132880 + ... + 43133387.

It is an arithmetic number, because the mean of its divisors is an integer number (4140780864).

Almost surely, 2^21911631818 is an apocalyptic number.

21911631818 is a deficient number, since it is larger than the sum of its proper divisors (11214615094).

21911631818 is a wasteful number, since it uses less digits than its factorization.

21911631818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86266396.

The product of its digits is 20736, while the sum is 41.

The spelling of 21911631818 in words is "twenty-one billion, nine hundred eleven million, six hundred thirty-one thousand, eight hundred eighteen".