19699991 has 4 divisors (see below), whose sum is σ = 20858832. Its totient is φ = 18541152.

The previous prime is 19699987. The next prime is 19699997. The reversal of 19699991 is 19999691.

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

It is not a de Polignac number, because 19699991 - 2² = 19699987 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 (19699997) 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, 579395 + ... + 579428.

It is an arithmetic number, because the mean of its divisors is an integer number (5214708).

Almost surely, 2^19699991 is an apocalyptic number.

19699991 is a deficient number, since it is larger than the sum of its proper divisors (1158841).

19699991 is a wasteful number, since it uses less digits than its factorization.

19699991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1158840.

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

The square root of 19699991 is about 4438.4671903710. The cubic root of 19699991 is about 270.0776685564.

The spelling of 19699991 in words is "nineteen million, six hundred ninety-nine thousand, nine hundred ninety-one".