19768991 has 4 divisors (see below), whose sum is σ = 21566184. Its totient is φ = 17971800.

The previous prime is 19768967. The next prime is 19768993. The reversal of 19768991 is 19986791.

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

It is not a de Polignac number, because 19768991 - 2⁶ = 19768927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19768993) 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, 898580 + ... + 898601.

It is an arithmetic number, because the mean of its divisors is an integer number (5391546).

Almost surely, 2^19768991 is an apocalyptic number.

19768991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

19768991 is a deficient number, since it is larger than the sum of its proper divisors (1797193).

19768991 is a wasteful number, since it uses less digits than its factorization.

19768991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1797192.

The product of its digits is 244944, while the sum is 50.

The square root of 19768991 is about 4446.2333497017. The cubic root of 19768991 is about 270.3926203812.

The spelling of 19768991 in words is "nineteen million, seven hundred sixty-eight thousand, nine hundred ninety-one".