18991445 has 16 divisors (see below), whose sum is σ = 25944192. Its totient is φ = 13210560.

The previous prime is 18991439. The next prime is 18991457. The reversal of 18991445 is 54419981.

It is not a de Polignac number, because 18991445 - 2⁴ = 18991429 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6242 + ... + 8771.

It is an arithmetic number, because the mean of its divisors is an integer number (1621512).

Almost surely, 2^18991445 is an apocalyptic number.

It is an amenable number.

18991445 is a deficient number, since it is larger than the sum of its proper divisors (6952747).

18991445 is a wasteful number, since it uses less digits than its factorization.

18991445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15052.

The product of its digits is 51840, while the sum is 41.

The square root of 18991445 is about 4357.9175072505. The cubic root of 18991445 is about 266.8001094280.

The spelling of 18991445 in words is "eighteen million, nine hundred ninety-one thousand, four hundred forty-five".