81517740 has 96 divisors (see below), whose sum is σ = 235920384. Its totient is φ = 21020160.

The previous prime is 81517739. The next prime is 81517741. The reversal of 81517740 is 4771518.

81517740 is digitally balanced in base 9, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (81517739) and next prime (81517741).

It is a super-3 number, since 3×81517740³ (a number of 25 digits) contains 333 as substring.

81517740 is strictly pandigital in base 9.

It is not an unprimeable number, because it can be changed into a prime (81517741) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 386235 + ... + 386445.

It is an arithmetic number, because the mean of its divisors is an integer number (2457504).

Almost surely, 2^81517740 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81517740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117960192).

81517740 is an abundant number, since it is smaller than the sum of its proper divisors (154402644).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81517740 is a wasteful number, since it uses less digits than its factorization.

81517740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407 (or 405 counting only the distinct ones).

The product of its (nonzero) digits is 7840, while the sum is 33.

The square root of 81517740 is about 9028.7175169013. The cubic root of 81517740 is about 433.5947784555.

The spelling of 81517740 in words is "eighty-one million, five hundred seventeen thousand, seven hundred forty".