19991093 has 4 divisors (see below), whose sum is σ = 20002668. Its totient is φ = 19979520.

The previous prime is 19991089. The next prime is 19991107. The reversal of 19991093 is 39019991.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 39019991 = 2237 ⋅17443.

It can be written as a sum of positive squares in 2 ways, for example, as 5299204 + 14691889 = 2302^2 + 3833^2 .

It is a cyclic number.

It is not a de Polignac number, because 19991093 - 2² = 19991089 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 19991093.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19991003) 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, 2618 + ... + 6843.

It is an arithmetic number, because the mean of its divisors is an integer number (5000667).

Almost surely, 2^19991093 is an apocalyptic number.

It is an amenable number.

19991093 is a deficient number, since it is larger than the sum of its proper divisors (11575).

19991093 is an equidigital number, since it uses as much as digits as its factorization.

19991093 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11574.

The product of its (nonzero) digits is 19683, while the sum is 41.

The square root of 19991093 is about 4471.1400112276. The cubic root of 19991093 is about 271.4014601466.

The spelling of 19991093 in words is "nineteen million, nine hundred ninety-one thousand, ninety-three".