81917701 has 4 divisors (see below), whose sum is σ = 83463372. Its totient is φ = 80372032.

The previous prime is 81917699. The next prime is 81917723. The reversal of 81917701 is 10771918.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 10771918 = 2 ⋅5385959.

It can be written as a sum of positive squares in 2 ways, for example, as 24900100 + 57017601 = 4990^2 + 7551^2 .

It is a cyclic number.

It is not a de Polignac number, because 81917701 - 2¹ = 81917699 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81917791) 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, 772756 + ... + 772861.

It is an arithmetic number, because the mean of its divisors is an integer number (20865843).

Almost surely, 2^81917701 is an apocalyptic number.

It is an amenable number.

81917701 is a deficient number, since it is larger than the sum of its proper divisors (1545671).

81917701 is a wasteful number, since it uses less digits than its factorization.

81917701 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1545670.

The product of its (nonzero) digits is 3528, while the sum is 34.

The square root of 81917701 is about 9050.8397952897. The cubic root of 81917701 is about 434.3027558267.

The spelling of 81917701 in words is "eighty-one million, nine hundred seventeen thousand, seven hundred one".