19999691 has 8 divisors (see below), whose sum is σ = 20280240. Its totient is φ = 19721088.

The previous prime is 19999663. The next prime is 19999697. The reversal of 19999691 is 19699991.

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

It is a cyclic number.

It is not a de Polignac number, because 19999691 - 2¹⁸ = 19737547 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19999697) 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, 43535 + ... + 43991.

It is an arithmetic number, because the mean of its divisors is an integer number (2535030).

Almost surely, 2^19999691 is an apocalyptic number.

19999691 is a deficient number, since it is larger than the sum of its proper divisors (280549).

19999691 is a wasteful number, since it uses less digits than its factorization.

19999691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 973.

The product of its digits is 354294, while the sum is 53.

The square root of 19999691 is about 4472.1014076159. The cubic root of 19999691 is about 271.4403637272.

The spelling of 19999691 in words is "nineteen million, nine hundred ninety-nine thousand, six hundred ninety-one".