191821161 has 16 divisors (see below), whose sum is σ = 293529600. Its totient is φ = 109150608.

The previous prime is 191821159. The next prime is 191821199. The reversal of 191821161 is 161128191.

It is a happy number.

It is not a de Polignac number, because 191821161 - 2¹ = 191821159 is a prime.

It is not an unprimeable number, because it can be changed into a prime (191821121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14091 + ... + 24128.

It is an arithmetic number, because the mean of its divisors is an integer number (18345600).

Almost surely, 2^191821161 is an apocalyptic number.

It is an amenable number.

191821161 is a deficient number, since it is larger than the sum of its proper divisors (101708439).

191821161 is a wasteful number, since it uses less digits than its factorization.

191821161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38468.

The product of its digits is 864, while the sum is 30.

The square root of 191821161 is about 13849.9516605655. The cubic root of 191821161 is about 576.7206540981.

The spelling of 191821161 in words is "one hundred ninety-one million, eight hundred twenty-one thousand, one hundred sixty-one".