81670871 has 2 divisors, whose sum is σ = 81670872. Its totient is φ = 81670870.

The previous prime is 81670859. The next prime is 81670879. The reversal of 81670871 is 17807618.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81670871 - 2⁶ = 81670807 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81670879) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40835435 + 40835436.

It is an arithmetic number, because the mean of its divisors is an integer number (40835436).

Almost surely, 2^81670871 is an apocalyptic number.

81670871 is a deficient number, since it is larger than the sum of its proper divisors (1).

81670871 is an equidigital number, since it uses as much as digits as its factorization.

81670871 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18816, while the sum is 38.

The square root of 81670871 is about 9037.1937569137. The cubic root of 81670871 is about 433.8661110918.

The spelling of 81670871 in words is "eighty-one million, six hundred seventy thousand, eight hundred seventy-one".