19997997 has 8 divisors (see below), whose sum is σ = 26685120. Its totient is φ = 13321440.

The previous prime is 19997993. The next prime is 19998029. The reversal of 19997997 is 79979991.

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

It is not a de Polignac number, because 19997997 - 2² = 19997993 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19997997.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19997993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4672 + ... + 7862.

It is an arithmetic number, because the mean of its divisors is an integer number (3335640).

Almost surely, 2^19997997 is an apocalyptic number.

It is an amenable number.

19997997 is a deficient number, since it is larger than the sum of its proper divisors (6687123).

19997997 is a wasteful number, since it uses less digits than its factorization.

19997997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5283.

The product of its digits is 2893401, while the sum is 60.

The square root of 19997997 is about 4471.9120071844. The cubic root of 19997997 is about 271.4326997262.

The spelling of 19997997 in words is "nineteen million, nine hundred ninety-seven thousand, nine hundred ninety-seven".