21131022166 has 4 divisors (see below), whose sum is σ = 31696533252. Its totient is φ = 10565511082.

The previous prime is 21131022149. The next prime is 21131022191. The reversal of 21131022166 is 66122013112.

It is a happy number.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21131022166.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 5282755540 + ... + 5282755543.

It is an arithmetic number, because the mean of its divisors is an integer number (7924133313).

Almost surely, 2^21131022166 is an apocalyptic number.

21131022166 is a deficient number, since it is larger than the sum of its proper divisors (10565511086).

21131022166 is a wasteful number, since it uses less digits than its factorization.

21131022166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10565511085.

The product of its (nonzero) digits is 864, while the sum is 25.

Adding to 21131022166 its reverse (66122013112), we get a palindrome (87253035278).

The spelling of 21131022166 in words is "twenty-one billion, one hundred thirty-one million, twenty-two thousand, one hundred sixty-six".