81701987 has 2 divisors, whose sum is σ = 81701988. Its totient is φ = 81701986.

The previous prime is 81701959. The next prime is 81701989. The reversal of 81701987 is 78910718.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81701987 - 2⁶ = 81701923 is a prime.

Together with 81701989, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81701989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40850993 + 40850994.

It is an arithmetic number, because the mean of its divisors is an integer number (40850994).

Almost surely, 2^81701987 is an apocalyptic number.

81701987 is a deficient number, since it is larger than the sum of its proper divisors (1).

81701987 is an equidigital number, since it uses as much as digits as its factorization.

81701987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28224, while the sum is 41.

The square root of 81701987 is about 9038.9151450824. The cubic root of 81701987 is about 433.9212040261.

The spelling of 81701987 in words is "eighty-one million, seven hundred one thousand, nine hundred eighty-seven".