191166021 has 16 divisors (see below), whose sum is σ = 284296320. Its totient is φ = 126954720.

The previous prime is 191165981. The next prime is 191166023. The reversal of 191166021 is 120661191.

It is not a de Polignac number, because 191166021 - 2⁹ = 191165509 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191166023) 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, 6360 + ... + 20561.

It is an arithmetic number, because the mean of its divisors is an integer number (17768520).

Almost surely, 2^191166021 is an apocalyptic number.

It is an amenable number.

191166021 is a deficient number, since it is larger than the sum of its proper divisors (93130299).

191166021 is a wasteful number, since it uses less digits than its factorization.

191166021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27193 (or 27187 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 191166021 is about 13826.2800854026. The cubic root of 191166021 is about 576.0633339647.

The spelling of 191166021 in words is "one hundred ninety-one million, one hundred sixty-six thousand, twenty-one".