21161231166 has 8 divisors (see below), whose sum is σ = 42322462344. Its totient is φ = 7053743720.

The previous prime is 21161231137. The next prime is 21161231173. The reversal of 21161231166 is 66113216112.

It is a happy number.

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

21161231166 is an admirable number.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1763435925 + ... + 1763435936.

It is an arithmetic number, because the mean of its divisors is an integer number (5290307793).

Almost surely, 2^21161231166 is an apocalyptic number.

21161231166 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21161231166 is a wasteful number, since it uses less digits than its factorization.

21161231166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3526871866.

The product of its digits is 2592, while the sum is 30.

Adding to 21161231166 its reverse (66113216112), we get a palindrome (87274447278).

The spelling of 21161231166 in words is "twenty-one billion, one hundred sixty-one million, two hundred thirty-one thousand, one hundred sixty-six".