18847861 has 2 divisors, whose sum is σ = 18847862. Its totient is φ = 18847860.

The previous prime is 18847819. The next prime is 18847891. The reversal of 18847861 is 16874881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15256836 + 3591025 = 3906^2 + 1895^2 .

It is a cyclic number.

It is not a de Polignac number, because 18847861 - 2⁷ = 18847733 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18847891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9423930 + 9423931.

It is an arithmetic number, because the mean of its divisors is an integer number (9423931).

Almost surely, 2^18847861 is an apocalyptic number.

It is an amenable number.

18847861 is a deficient number, since it is larger than the sum of its proper divisors (1).

18847861 is an equidigital number, since it uses as much as digits as its factorization.

18847861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 86016, while the sum is 43.

The square root of 18847861 is about 4341.4123278030. The cubic root of 18847861 is about 266.1260308795.

The spelling of 18847861 in words is "eighteen million, eight hundred forty-seven thousand, eight hundred sixty-one".