19805997 has 4 divisors (see below), whose sum is σ = 26408000. Its totient is φ = 13203996.

The previous prime is 19805987. The next prime is 19806001. The reversal of 19805997 is 79950891.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 19805997 - 2¹⁴ = 19789613 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 (19805917) 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, 3300997 + ... + 3301002.

It is an arithmetic number, because the mean of its divisors is an integer number (6602000).

Almost surely, 2^19805997 is an apocalyptic number.

It is an amenable number.

19805997 is a deficient number, since it is larger than the sum of its proper divisors (6602003).

19805997 is an equidigital number, since it uses as much as digits as its factorization.

19805997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6602002.

The product of its (nonzero) digits is 204120, while the sum is 48.

The square root of 19805997 is about 4450.3929040030. The cubic root of 19805997 is about 270.5612331380.

It can be divided in two parts, 19805 and 997, that added together give a palindrome (20802).

The spelling of 19805997 in words is "nineteen million, eight hundred five thousand, nine hundred ninety-seven".