181861387 has 2 divisors, whose sum is σ = 181861388. Its totient is φ = 181861386.

The previous prime is 181861357. The next prime is 181861403. The reversal of 181861387 is 783168181.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 181861387 - 2⁷ = 181861259 is a prime.

It is not a weakly prime, because it can be changed into another prime (181861357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90930693 + 90930694.

It is an arithmetic number, because the mean of its divisors is an integer number (90930694).

Almost surely, 2^181861387 is an apocalyptic number.

181861387 is a deficient number, since it is larger than the sum of its proper divisors (1).

181861387 is an equidigital number, since it uses as much as digits as its factorization.

181861387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64512, while the sum is 43.

The square root of 181861387 is about 13485.5992451207. The cubic root of 181861387 is about 566.5612048644.

The spelling of 181861387 in words is "one hundred eighty-one million, eight hundred sixty-one thousand, three hundred eighty-seven".