18973861 has 4 divisors (see below), whose sum is σ = 18997632. Its totient is φ = 18950092.

The previous prime is 18973831. The next prime is 18973897. The reversal of 18973861 is 16837981.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 16837981 = 79 ⋅213139.

It is a cyclic number.

It is not a de Polignac number, because 18973861 - 2⁹ = 18973349 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 (18973831) 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, 10645 + ... + 12298.

It is an arithmetic number, because the mean of its divisors is an integer number (4749408).

Almost surely, 2^18973861 is an apocalyptic number.

It is an amenable number.

18973861 is a deficient number, since it is larger than the sum of its proper divisors (23771).

18973861 is an equidigital number, since it uses as much as digits as its factorization.

18973861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23770.

The product of its digits is 72576, while the sum is 43.

The square root of 18973861 is about 4355.8995626621. The cubic root of 18973861 is about 266.7177414323.

The spelling of 18973861 in words is "eighteen million, nine hundred seventy-three thousand, eight hundred sixty-one".