81517604 has 48 divisors (see below), whose sum is σ = 167626368. Its totient is φ = 33965568.

The previous prime is 81517571. The next prime is 81517607. The reversal of 81517604 is 40671518.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (81517607) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 241724 + ... + 242060.

It is an arithmetic number, because the mean of its divisors is an integer number (3492216).

Almost surely, 2^81517604 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 81517604, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (83813184).

81517604 is an abundant number, since it is smaller than the sum of its proper divisors (86108764).

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

81517604 is a wasteful number, since it uses less digits than its factorization.

81517604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 564 (or 562 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 32.

The square root of 81517604 is about 9028.7099853744. The cubic root of 81517604 is about 433.5945373263.

The spelling of 81517604 in words is "eighty-one million, five hundred seventeen thousand, six hundred four".