81503617 has 4 divisors (see below), whose sum is σ = 87773140. Its totient is φ = 75234096.

The previous prime is 81503581. The next prime is 81503621. The reversal of 81503617 is 71630518.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 24591681 + 56911936 = 4959^2 + 7544^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81503617 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81501617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3134742 + ... + 3134767.

It is an arithmetic number, because the mean of its divisors is an integer number (21943285).

Almost surely, 2^81503617 is an apocalyptic number.

It is an amenable number.

81503617 is a deficient number, since it is larger than the sum of its proper divisors (6269523).

81503617 is a wasteful number, since it uses less digits than its factorization.

81503617 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6269522.

The product of its (nonzero) digits is 5040, while the sum is 31.

The square root of 81503617 is about 9027.9353675134. The cubic root of 81503617 is about 433.5697368194.

The spelling of 81503617 in words is "eighty-one million, five hundred three thousand, six hundred seventeen".