81658166 has 4 divisors (see below), whose sum is σ = 122487252. Its totient is φ = 40829082.

The previous prime is 81658163. The next prime is 81658169. The reversal of 81658166 is 66185618.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 66185618 = 2 ⋅33092809.

It is an interprime number because it is at equal distance from previous prime (81658163) and next prime (81658169).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81658163) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20414540 + ... + 20414543.

It is an arithmetic number, because the mean of its divisors is an integer number (30621813).

Almost surely, 2^81658166 is an apocalyptic number.

81658166 is a deficient number, since it is larger than the sum of its proper divisors (40829086).

81658166 is a wasteful number, since it uses less digits than its factorization.

81658166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40829085.

The product of its digits is 69120, while the sum is 41.

The square root of 81658166 is about 9036.4908011905. The cubic root of 81658166 is about 433.8436120264.

The spelling of 81658166 in words is "eighty-one million, six hundred fifty-eight thousand, one hundred sixty-six".