81745791 has 8 divisors (see below), whose sum is σ = 112510464. Its totient is φ = 52739160.

The previous prime is 81745777. The next prime is 81745793. The reversal of 81745791 is 19754718.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81745791 - 2¹³ = 81737599 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81745793) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 439401 + ... + 439586.

It is an arithmetic number, because the mean of its divisors is an integer number (14063808).

Almost surely, 2^81745791 is an apocalyptic number.

81745791 is a deficient number, since it is larger than the sum of its proper divisors (30764673).

81745791 is a wasteful number, since it uses less digits than its factorization.

81745791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 879021.

The product of its digits is 70560, while the sum is 42.

The square root of 81745791 is about 9041.3378987847. The cubic root of 81745791 is about 433.9987382013.

The spelling of 81745791 in words is "eighty-one million, seven hundred forty-five thousand, seven hundred ninety-one".