18991372 has 12 divisors (see below), whose sum is σ = 33281136. Its totient is φ = 9482480.

The previous prime is 18991361. The next prime is 18991373. The reversal of 18991372 is 27319981.

It is not an unprimeable number, because it can be changed into a prime (18991373) 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, 393 + ... + 6175.

It is an arithmetic number, because the mean of its divisors is an integer number (2773428).

Almost surely, 2^18991372 is an apocalyptic number.

It is an amenable number.

18991372 is a deficient number, since it is larger than the sum of its proper divisors (14289764).

18991372 is a wasteful number, since it uses less digits than its factorization.

18991372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6608 (or 6606 counting only the distinct ones).

The product of its digits is 27216, while the sum is 40.

The square root of 18991372 is about 4357.9091316823. The cubic root of 18991372 is about 266.7997675823.

The spelling of 18991372 in words is "eighteen million, nine hundred ninety-one thousand, three hundred seventy-two".