1999229991 has 16 divisors (see below), whose sum is σ = 2986566528. Its totient is φ = 1178906400.

The previous prime is 1999229983. The next prime is 1999230001.

It is a happy number.

1999229991 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1999229991 - 2³ = 1999229983 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1999229591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 817465 + ... + 819906.

It is an arithmetic number, because the mean of its divisors is an integer number (186660408).

Almost surely, 2^1999229991 is an apocalyptic number.

1999229991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1999229991 is a deficient number, since it is larger than the sum of its proper divisors (987336537).

1999229991 is a wasteful number, since it uses less digits than its factorization.

1999229991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1637422.

The product of its digits is 2125764, while the sum is 60.

The square root of 1999229991 is about 44712.7497588775. The cubic root of 1999229991 is about 1259.7593373818.

The spelling of 1999229991 in words is "one billion, nine hundred ninety-nine million, two hundred twenty-nine thousand, nine hundred ninety-one".