19987973 has 4 divisors (see below), whose sum is σ = 19999980. Its totient is φ = 19975968.

The previous prime is 19987969. The next prime is 19987993. The reversal of 19987973 is 37978991.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10975969 + 9012004 = 3313^2 + 3002^2 .

It is a cyclic number.

It is not a de Polignac number, because 19987973 - 2² = 19987969 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 (19987993) 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, 3008 + ... + 7001.

It is an arithmetic number, because the mean of its divisors is an integer number (4999995).

Almost surely, 2^19987973 is an apocalyptic number.

It is an amenable number.

19987973 is a deficient number, since it is larger than the sum of its proper divisors (12007).

19987973 is a wasteful number, since it uses less digits than its factorization.

19987973 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12006.

The product of its digits is 857304, while the sum is 53.

The square root of 19987973 is about 4470.7910933078. The cubic root of 19987973 is about 271.3873402481.

The spelling of 19987973 in words is "nineteen million, nine hundred eighty-seven thousand, nine hundred seventy-three".