18991901 has 8 divisors (see below), whose sum is σ = 19473024. Its totient is φ = 18514080.

The previous prime is 18991891. The next prime is 18991909. The reversal of 18991901 is 10919981.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18991901 - 2¹⁸ = 18729757 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 (18991909) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14066 + ... + 15356.

It is an arithmetic number, because the mean of its divisors is an integer number (2434128).

Almost surely, 2^18991901 is an apocalyptic number.

It is an amenable number.

18991901 is a deficient number, since it is larger than the sum of its proper divisors (481123).

18991901 is a wasteful number, since it uses less digits than its factorization.

18991901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1651.

The product of its (nonzero) digits is 5832, while the sum is 38.

The square root of 18991901 is about 4357.9698255036. The cubic root of 18991901 is about 266.8022447733.

The spelling of 18991901 in words is "eighteen million, nine hundred ninety-one thousand, nine hundred one".