81680769 has 12 divisors (see below), whose sum is σ = 119918292. Its totient is φ = 53560800.

The previous prime is 81680761. The next prime is 81680771. The reversal of 81680769 is 96708618.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 25250625 + 56430144 = 5025^2 + 7512^2 .

It is not a de Polignac number, because 81680769 - 2³ = 81680761 is a prime.

It is a super-2 number, since 2×81680769² = 13343496048862722, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81680761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 73842 + ... + 74939.

It is an arithmetic number, because the mean of its divisors is an integer number (9993191).

Almost surely, 2^81680769 is an apocalyptic number.

It is an amenable number.

81680769 is a deficient number, since it is larger than the sum of its proper divisors (38237523).

81680769 is a wasteful number, since it uses less digits than its factorization.

81680769 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148848 (or 148845 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 45.

The square root of 81680769 is about 9037.7413660715. The cubic root of 81680769 is about 433.8836376724.

The spelling of 81680769 in words is "eighty-one million, six hundred eighty thousand, seven hundred sixty-nine".