18999973 has 2 divisors, whose sum is σ = 18999974. Its totient is φ = 18999972.

The previous prime is 18999971. The next prime is 18999977. The reversal of 18999973 is 37999981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10131489 + 8868484 = 3183^2 + 2978^2 .

It is a cyclic number.

It is not a de Polignac number, because 18999973 - 2¹ = 18999971 is a prime.

Together with 18999971, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18999971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9499986 + 9499987.

It is an arithmetic number, because the mean of its divisors is an integer number (9499987).

Almost surely, 2^18999973 is an apocalyptic number.

It is an amenable number.

18999973 is a deficient number, since it is larger than the sum of its proper divisors (1).

18999973 is an equidigital number, since it uses as much as digits as its factorization.

18999973 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1102248, while the sum is 55.

The square root of 18999973 is about 4358.8958464272. The cubic root of 18999973 is about 266.8400384742.

The spelling of 18999973 in words is "eighteen million, nine hundred ninety-nine thousand, nine hundred seventy-three".