19901997 has 8 divisors (see below), whose sum is σ = 29484480. Its totient is φ = 13267980.

The previous prime is 19901963. The next prime is 19902011. The reversal of 19901997 is 79910991.

It is not a de Polignac number, because 19901997 - 2¹⁰ = 19900973 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19901927) 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, 368529 + ... + 368582.

It is an arithmetic number, because the mean of its divisors is an integer number (3685560).

Almost surely, 2^19901997 is an apocalyptic number.

It is an amenable number.

19901997 is a deficient number, since it is larger than the sum of its proper divisors (9582483).

19901997 is an equidigital number, since it uses as much as digits as its factorization.

19901997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 737120 (or 737114 counting only the distinct ones).

The product of its (nonzero) digits is 45927, while the sum is 45.

The square root of 19901997 is about 4461.1654306919. The cubic root of 19901997 is about 270.9976670415.

The spelling of 19901997 in words is "nineteen million, nine hundred one thousand, nine hundred ninety-seven".