19691999 has 8 divisors (see below), whose sum is σ = 20979840. Its totient is φ = 18429336.

The previous prime is 19691993. The next prime is 19692007. The reversal of 19691999 is 99919691.

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 19691999 - 2¹² = 19687903 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 19691999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19691993) 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, 4667 + ... + 7820.

It is an arithmetic number, because the mean of its divisors is an integer number (2622480).

Almost surely, 2^19691999 is an apocalyptic number.

19691999 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

19691999 is a deficient number, since it is larger than the sum of its proper divisors (1287841).

19691999 is a wasteful number, since it uses less digits than its factorization.

19691999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12589.

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

The square root of 19691999 is about 4437.5667882298. The cubic root of 19691999 is about 270.0411414216.

The spelling of 19691999 in words is "nineteen million, six hundred ninety-one thousand, nine hundred ninety-nine".