191999997 has 64 divisors (see below), whose sum is σ = 345702400. Its totient is φ = 102876480.

The previous prime is 191999987. The next prime is 192000043. The reversal of 191999997 is 799999191.

It is not a de Polignac number, because 191999997 - 2⁷ = 191999869 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a nude number because it is divisible by every one of its digits.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191999917) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 455847 + ... + 456267.

It is an arithmetic number, because the mean of its divisors is an integer number (5401600).

Almost surely, 2^191999997 is an apocalyptic number.

It is an amenable number.

191999997 is a deficient number, since it is larger than the sum of its proper divisors (153702403).

191999997 is a wasteful number, since it uses less digits than its factorization.

191999997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 583 (or 577 counting only the distinct ones).

The product of its digits is 3720087, while the sum is 63.

The square root of 191999997 is about 13856.4063522978. The cubic root of 191999997 is about 576.8998251183.

The spelling of 191999997 in words is "one hundred ninety-one million, nine hundred ninety-nine thousand, nine hundred ninety-seven".