198051991 has 8 divisors (see below), whose sum is σ = 215665200. Its totient is φ = 181157760.

The previous prime is 198051983. The next prime is 198052003. The reversal of 198051991 is 199150891.

198051991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 198051991 - 2³ = 198051983 is a prime.

It is a super-2 number, since 2×198051991² = 78449182278128162, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (198054991) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 179170 + ... + 180271.

It is an arithmetic number, because the mean of its divisors is an integer number (26958150).

Almost surely, 2^198051991 is an apocalyptic number.

198051991 is a deficient number, since it is larger than the sum of its proper divisors (17613209).

198051991 is a wasteful number, since it uses less digits than its factorization.

198051991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 359489.

The product of its (nonzero) digits is 29160, while the sum is 43.

The square root of 198051991 is about 14073.0945779526. The cubic root of 198051991 is about 582.8986787312.

The spelling of 198051991 in words is "one hundred ninety-eight million, fifty-one thousand, nine hundred ninety-one".