81409187 has 2 divisors, whose sum is σ = 81409188. Its totient is φ = 81409186.

The previous prime is 81409117. The next prime is 81409189. The reversal of 81409187 is 78190418.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81409187 - 2¹⁰ = 81408163 is a prime.

Together with 81409189, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81409187.

It is not a weakly prime, because it can be changed into another prime (81409189) 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, 40704593 + 40704594.

It is an arithmetic number, because the mean of its divisors is an integer number (40704594).

Almost surely, 2^81409187 is an apocalyptic number.

81409187 is a deficient number, since it is larger than the sum of its proper divisors (1).

81409187 is an equidigital number, since it uses as much as digits as its factorization.

81409187 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16128, while the sum is 38.

The square root of 81409187 is about 9022.7039738650. The cubic root of 81409187 is about 433.4022276392.

The spelling of 81409187 in words is "eighty-one million, four hundred nine thousand, one hundred eighty-seven".