19116991 has 4 divisors (see below), whose sum is σ = 19231632. Its totient is φ = 19002352.

The previous prime is 19116967. The next prime is 19116997. The reversal of 19116991 is 19961191.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 19116991 - 2⁹ = 19116479 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 19116991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19116997) 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, 57070 + ... + 57403.

It is an arithmetic number, because the mean of its divisors is an integer number (4807908).

Almost surely, 2^19116991 is an apocalyptic number.

19116991 is a deficient number, since it is larger than the sum of its proper divisors (114641).

19116991 is a wasteful number, since it uses less digits than its factorization.

19116991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114640.

The product of its digits is 4374, while the sum is 37.

The square root of 19116991 is about 4372.2981371357. The cubic root of 19116991 is about 267.3867270143.

The spelling of 19116991 in words is "nineteen million, one hundred sixteen thousand, nine hundred ninety-one".