81717345 has 12 divisors (see below), whose sum is σ = 141643476. Its totient is φ = 43582560.

The previous prime is 81717343. The next prime is 81717353. The reversal of 81717345 is 54371718.

It can be written as a sum of positive squares in 2 ways, for example, as 62110161 + 19607184 = 7881^2 + 4428^2 .

It is not a de Polignac number, because 81717345 - 2¹ = 81717343 is a prime.

It is a super-3 number, since 3×81717345³ (a number of 25 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (81717343) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 907926 + ... + 908015.

It is an arithmetic number, because the mean of its divisors is an integer number (11803623).

Almost surely, 2^81717345 is an apocalyptic number.

It is an amenable number.

81717345 is a deficient number, since it is larger than the sum of its proper divisors (59926131).

81717345 is a wasteful number, since it uses less digits than its factorization.

81717345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1815952 (or 1815949 counting only the distinct ones).

The product of its digits is 23520, while the sum is 36.

The square root of 81717345 is about 9039.7646540162. The cubic root of 81717345 is about 433.9483912243.

The spelling of 81717345 in words is "eighty-one million, seven hundred seventeen thousand, three hundred forty-five".