19910091 has 8 divisors (see below), whose sum is σ = 27403264. Its totient is φ = 12845160.

The previous prime is 19910089. The next prime is 19910113. The reversal of 19910091 is 19001991.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 19910091 - 2¹ = 19910089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19910491) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 106951 + ... + 107136.

It is an arithmetic number, because the mean of its divisors is an integer number (3425408).

Almost surely, 2^19910091 is an apocalyptic number.

19910091 is a deficient number, since it is larger than the sum of its proper divisors (7493173).

19910091 is a wasteful number, since it uses less digits than its factorization.

19910091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214121.

The product of its (nonzero) digits is 729, while the sum is 30.

The square root of 19910091 is about 4462.0725005316. The cubic root of 19910091 is about 271.0343996673.

It can be divided in two parts, 1991009 and 1, that added together give a triangular number (1991010 = T₁₉₉₅).

The spelling of 19910091 in words is "nineteen million, nine hundred ten thousand, ninety-one".