91999919 has 32 divisors (see below), whose sum is σ = 112147200. Its totient is φ = 74511360.

The previous prime is 91999907. The next prime is 91999951.

91999919 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 91999919 - 2²⁴ = 75222703 is a prime.

It is a super-2 number, since 2×91999919² = 16927970192013122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91999969) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 260447 + ... + 260799.

It is an arithmetic number, because the mean of its divisors is an integer number (3504600).

Almost surely, 2^91999919 is an apocalyptic number.

91999919 is a deficient number, since it is larger than the sum of its proper divisors (20147281).

91999919 is a wasteful number, since it uses less digits than its factorization.

91999919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 455.

The product of its digits is 531441, while the sum is 56.

The square root of 91999919 is about 9591.6588242076. The cubic root of 91999919 is about 451.4356110608.

The spelling of 91999919 in words is "ninety-one million, nine hundred ninety-nine thousand, nine hundred nineteen".