81670943 has 2 divisors, whose sum is σ = 81670944. Its totient is φ = 81670942.

The previous prime is 81670909. The next prime is 81670973. The reversal of 81670943 is 34907618.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81670943 - 2⁶ = 81670879 is a prime.

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

It is a junction number, because it is equal to n+sod(n) for n = 81670897 and 81670906.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81670973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40835471 + 40835472.

It is an arithmetic number, because the mean of its divisors is an integer number (40835472).

Almost surely, 2^81670943 is an apocalyptic number.

81670943 is a deficient number, since it is larger than the sum of its proper divisors (1).

81670943 is an equidigital number, since it uses as much as digits as its factorization.

81670943 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36288, while the sum is 38.

The square root of 81670943 is about 9037.1977404503. The cubic root of 81670943 is about 433.8662385887.

The spelling of 81670943 in words is "eighty-one million, six hundred seventy thousand, nine hundred forty-three".