19973999 has 4 divisors (see below), whose sum is σ = 19983600. Its totient is φ = 19964400.

The previous prime is 19973977. The next prime is 19974001. The reversal of 19973999 is 99937991.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 19973999 - 2⁸ = 19973743 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 (19973939) 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, 227 + ... + 6324.

It is an arithmetic number, because the mean of its divisors is an integer number (4995900).

Almost surely, 2^19973999 is an apocalyptic number.

19973999 is a deficient number, since it is larger than the sum of its proper divisors (9601).

19973999 is an equidigital number, since it uses as much as digits as its factorization.

19973999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9600.

The product of its digits is 1240029, while the sum is 56.

The square root of 19973999 is about 4469.2280093994. The cubic root of 19973999 is about 271.3240813606.

The spelling of 19973999 in words is "nineteen million, nine hundred seventy-three thousand, nine hundred ninety-nine".