18661789 has 4 divisors (see below), whose sum is σ = 18691456. Its totient is φ = 18632124.

The previous prime is 18661771. The next prime is 18661807. The reversal of 18661789 is 98716681.

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.

It is an interprime number because it is at equal distance from previous prime (18661771) and next prime (18661807).

It is a cyclic number.

It is not a de Polignac number, because 18661789 - 2⁷ = 18661661 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 (18661739) 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, 13869 + ... + 15154.

It is an arithmetic number, because the mean of its divisors is an integer number (4672864).

Almost surely, 2^18661789 is an apocalyptic number.

It is an amenable number.

18661789 is a deficient number, since it is larger than the sum of its proper divisors (29667).

18661789 is an equidigital number, since it uses as much as digits as its factorization.

18661789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29666.

The product of its digits is 145152, while the sum is 46.

The square root of 18661789 is about 4319.9292818286. The cubic root of 18661789 is about 265.2473731390.

It can be divided in two parts, 1866 and 1789, that added together give a triangular number (3655 = T₈₅).

The spelling of 18661789 in words is "eighteen million, six hundred sixty-one thousand, seven hundred eighty-nine".