18919973 has 2 divisors, whose sum is σ = 18919974. Its totient is φ = 18919972.

The previous prime is 18919969. The next prime is 18919981. The reversal of 18919973 is 37991981.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14455204 + 4464769 = 3802^2 + 2113^2 .

It is a cyclic number.

It is not a de Polignac number, because 18919973 - 2² = 18919969 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18919673) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9459986 + 9459987.

It is an arithmetic number, because the mean of its divisors is an integer number (9459987).

Almost surely, 2^18919973 is an apocalyptic number.

It is an amenable number.

18919973 is a deficient number, since it is larger than the sum of its proper divisors (1).

18919973 is an equidigital number, since it uses as much as digits as its factorization.

18919973 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 122472, while the sum is 47.

The square root of 18919973 is about 4349.7095305319. The cubic root of 18919973 is about 266.4649987414.

The spelling of 18919973 in words is "eighteen million, nine hundred nineteen thousand, nine hundred seventy-three".