199186021 has 4 divisors (see below), whose sum is σ = 199295712. Its totient is φ = 199076332.

The previous prime is 199185989. The next prime is 199186033. The reversal of 199186021 is 120681991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 120681991 = 271 ⋅445321.

It is a cyclic number.

It is not a de Polignac number, because 199186021 - 2⁵ = 199185989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199186061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 52075 + ... + 55768.

It is an arithmetic number, because the mean of its divisors is an integer number (49823928).

Almost surely, 2^199186021 is an apocalyptic number.

It is an amenable number.

199186021 is a deficient number, since it is larger than the sum of its proper divisors (109691).

199186021 is a wasteful number, since it uses less digits than its factorization.

199186021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109690.

The product of its (nonzero) digits is 7776, while the sum is 37.

The square root of 199186021 is about 14113.3277790888. The cubic root of 199186021 is about 584.0091058895.

The spelling of 199186021 in words is "one hundred ninety-nine million, one hundred eighty-six thousand, twenty-one".