81432187 has 2 divisors, whose sum is σ = 81432188. Its totient is φ = 81432186.

The previous prime is 81432163. The next prime is 81432199. The reversal of 81432187 is 78123418.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81432187 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is equal to p_4748263 and since 81432187 and 4748263 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (81432107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40716093 + 40716094.

It is an arithmetic number, because the mean of its divisors is an integer number (40716094).

Almost surely, 2^81432187 is an apocalyptic number.

81432187 is a deficient number, since it is larger than the sum of its proper divisors (1).

81432187 is an equidigital number, since it uses as much as digits as its factorization.

81432187 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10752, while the sum is 34.

The square root of 81432187 is about 9023.9784463395. The cubic root of 81432187 is about 433.4430392191.

The spelling of 81432187 in words is "eighty-one million, four hundred thirty-two thousand, one hundred eighty-seven".