19911057 has 8 divisors (see below), whose sum is σ = 26601120. Its totient is φ = 13247520.

The previous prime is 19911049. The next prime is 19911091. The reversal of 19911057 is 75011991.

It is a happy number.

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

It is not a de Polignac number, because 19911057 - 2³ = 19911049 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (19911457) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4807 + ... + 7932.

It is an arithmetic number, because the mean of its divisors is an integer number (3325140).

Almost surely, 2^19911057 is an apocalyptic number.

It is an amenable number.

19911057 is a deficient number, since it is larger than the sum of its proper divisors (6690063).

19911057 is a wasteful number, since it uses less digits than its factorization.

19911057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13263.

The product of its (nonzero) digits is 2835, while the sum is 33.

The square root of 19911057 is about 4462.1807448825. The cubic root of 19911057 is about 271.0387829555.

The spelling of 19911057 in words is "nineteen million, nine hundred eleven thousand, fifty-seven".