18651881 has 2 divisors, whose sum is σ = 18651882. Its totient is φ = 18651880.

The previous prime is 18651877. The next prime is 18651887. The reversal of 18651881 is 18815681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18627856 + 24025 = 4316^2 + 155^2 .

It is a cyclic number.

It is not a de Polignac number, because 18651881 - 2² = 18651877 is a prime.

It is a super-2 number, since 2×18651881² = 695785329676322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18651887) 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 as a sum of consecutive naturals, namely, 9325940 + 9325941.

It is an arithmetic number, because the mean of its divisors is an integer number (9325941).

Almost surely, 2^18651881 is an apocalyptic number.

It is an amenable number.

18651881 is a deficient number, since it is larger than the sum of its proper divisors (1).

18651881 is an equidigital number, since it uses as much as digits as its factorization.

18651881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15360, while the sum is 38.

The square root of 18651881 is about 4318.7823515431. The cubic root of 18651881 is about 265.2004227240.

The spelling of 18651881 in words is "eighteen million, six hundred fifty-one thousand, eight hundred eighty-one".