191999988 has 72 divisors (see below), whose sum is σ = 512768256. Its totient is φ = 60480000.

The previous prime is 191999987. The next prime is 192000043. The reversal of 191999988 is 889999191.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191999987) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 45988 + ... + 49988.

Almost surely, 2^191999988 is an apocalyptic number.

191999988 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 191999988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (256384128).

191999988 is an abundant number, since it is smaller than the sum of its proper divisors (320768268).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

191999988 is a wasteful number, since it uses less digits than its factorization.

191999988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4085 (or 4080 counting only the distinct ones).

The product of its digits is 3779136, while the sum is 63.

The square root of 191999988 is about 13856.4060275383. The cubic root of 191999988 is about 576.8998161042.

The spelling of 191999988 in words is "one hundred ninety-one million, nine hundred ninety-nine thousand, nine hundred eighty-eight".