18691971 has 8 divisors (see below), whose sum is σ = 25502400. Its totient is φ = 12171432.

The previous prime is 18691963. The next prime is 18691973. The reversal of 18691971 is 17919681.

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

It is not a de Polignac number, because 18691971 - 2³ = 18691963 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18691973) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 72321 + ... + 72578.

It is an arithmetic number, because the mean of its divisors is an integer number (3187800).

Almost surely, 2^18691971 is an apocalyptic number.

18691971 is a deficient number, since it is larger than the sum of its proper divisors (6810429).

18691971 is a wasteful number, since it uses less digits than its factorization.

18691971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144945.

The product of its digits is 27216, while the sum is 42.

The square root of 18691971 is about 4323.4212147326. The cubic root of 18691971 is about 265.3902923446.

The spelling of 18691971 in words is "eighteen million, six hundred ninety-one thousand, nine hundred seventy-one".