81681164 has 12 divisors (see below), whose sum is σ = 143229744. Its totient is φ = 40758384.

The previous prime is 81681121. The next prime is 81681167. The reversal of 81681164 is 46118618.

It is a happy number.

It is a hoax number, since the sum of its digits (35) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (81681167) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18287 + ... + 22310.

It is an arithmetic number, because the mean of its divisors is an integer number (11935812).

Almost surely, 2^81681164 is an apocalyptic number.

It is an amenable number.

81681164 is a deficient number, since it is larger than the sum of its proper divisors (61548580).

81681164 is a wasteful number, since it uses less digits than its factorization.

81681164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41104 (or 41102 counting only the distinct ones).

The product of its digits is 9216, while the sum is 35.

The square root of 81681164 is about 9037.7632188501. The cubic root of 81681164 is about 433.8843370771.

The spelling of 81681164 in words is "eighty-one million, six hundred eighty-one thousand, one hundred sixty-four".