19971997 has 8 divisors (see below), whose sum is σ = 20403576. Its totient is φ = 19544832.

The previous prime is 19971989. The next prime is 19972003. The reversal of 19971997 is 79917991.

It can be written as a sum of positive squares in 4 ways, for example, as 488601 + 19483396 = 699^2 + 4414^2 .

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 19971997 - 2³ = 19971989 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 (19971947) 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, 9003 + ... + 10999.

It is an arithmetic number, because the mean of its divisors is an integer number (2550447).

Almost surely, 2^19971997 is an apocalyptic number.

It is an amenable number.

19971997 is a deficient number, since it is larger than the sum of its proper divisors (431579).

19971997 is a wasteful number, since it uses less digits than its factorization.

19971997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2207.

The product of its digits is 321489, while the sum is 52.

The square root of 19971997 is about 4469.0040277449. The cubic root of 19971997 is about 271.3150160926.

The spelling of 19971997 in words is "nineteen million, nine hundred seventy-one thousand, nine hundred ninety-seven".