18871789 has 2 divisors, whose sum is σ = 18871790. Its totient is φ = 18871788.

The previous prime is 18871781. The next prime is 18871841. The reversal of 18871789 is 98717881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12369289 + 6502500 = 3517^2 + 2550^2 .

It is a cyclic number.

It is not a de Polignac number, because 18871789 - 2³ = 18871781 is a prime.

It is a super-2 number, since 2×18871789² = 712288840121042, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18871781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9435894 + 9435895.

It is an arithmetic number, because the mean of its divisors is an integer number (9435895).

Almost surely, 2^18871789 is an apocalyptic number.

It is an amenable number.

18871789 is a deficient number, since it is larger than the sum of its proper divisors (1).

18871789 is an equidigital number, since it uses as much as digits as its factorization.

18871789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 225792, while the sum is 49.

The square root of 18871789 is about 4344.1672389539. The cubic root of 18871789 is about 266.2386019352.

The spelling of 18871789 in words is "eighteen million, eight hundred seventy-one thousand, seven hundred eighty-nine".