81793691 has 6 divisors (see below), whose sum is σ = 95147820. Its totient is φ = 70108836.

The previous prime is 81793669. The next prime is 81793693. The reversal of 81793691 is 19639718.

It is not a de Polignac number, because 81793691 - 2¹⁴ = 81777307 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81793693) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 834581 + ... + 834678.

It is an arithmetic number, because the mean of its divisors is an integer number (15857970).

Almost surely, 2^81793691 is an apocalyptic number.

81793691 is a deficient number, since it is larger than the sum of its proper divisors (13354129).

81793691 is a wasteful number, since it uses less digits than its factorization.

81793691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1669273 (or 1669266 counting only the distinct ones).

The product of its digits is 81648, while the sum is 44.

The square root of 81793691 is about 9043.9864550982. The cubic root of 81793691 is about 434.0834907012.

The spelling of 81793691 in words is "eighty-one million, seven hundred ninety-three thousand, six hundred ninety-one".