81738091 has 4 divisors (see below), whose sum is σ = 86546232. Its totient is φ = 76929952.

The previous prime is 81738073. The next prime is 81738121. The reversal of 81738091 is 19083718.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81738091 - 2⁷ = 81737963 is a prime.

It is a super-2 number, since 2×81738091² = 13362231040648562, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81738091.

It is not an unprimeable number, because it can be changed into a prime (81738001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2404045 + ... + 2404078.

It is an arithmetic number, because the mean of its divisors is an integer number (21636558).

Almost surely, 2^81738091 is an apocalyptic number.

81738091 is a deficient number, since it is larger than the sum of its proper divisors (4808141).

81738091 is a wasteful number, since it uses less digits than its factorization.

81738091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4808140.

The product of its (nonzero) digits is 12096, while the sum is 37.

The square root of 81738091 is about 9040.9120668216. The cubic root of 81738091 is about 433.9851110156.

The spelling of 81738091 in words is "eighty-one million, seven hundred thirty-eight thousand, ninety-one".