199978993 has 4 divisors (see below), whose sum is σ = 201176640. Its totient is φ = 198781348.

The previous prime is 199978991. The next prime is 199979023. The reversal of 199978993 is 399879991.

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.

It is a cyclic number.

It is not a de Polignac number, because 199978993 - 2¹ = 199978991 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (199978991) 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, 598573 + ... + 598906.

It is an arithmetic number, because the mean of its divisors is an integer number (50294160).

Almost surely, 2^199978993 is an apocalyptic number.

It is an amenable number.

199978993 is a deficient number, since it is larger than the sum of its proper divisors (1197647).

199978993 is a wasteful number, since it uses less digits than its factorization.

199978993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1197646.

The product of its digits is 9920232, while the sum is 64.

The square root of 199978993 is about 14141.3928946197. The cubic root of 199978993 is about 584.7830719788.

The spelling of 199978993 in words is "one hundred ninety-nine million, nine hundred seventy-eight thousand, nine hundred ninety-three".