81568516 has 36 divisors (see below), whose sum is σ = 155424276. Its totient is φ = 37427200.

The previous prime is 81568493. The next prime is 81568517. The reversal of 81568516 is 61586518.

It can be written as a sum of positive squares in 6 ways, for example, as 1537600 + 80030916 = 1240^2 + 8946^2 .

Its product of digits (57600) is a multiple of the sum of its prime factors (1800).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81568517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 46536 + ... + 48256.

It is an arithmetic number, because the mean of its divisors is an integer number (4317341).

Almost surely, 2^81568516 is an apocalyptic number.

It is an amenable number.

81568516 is a deficient number, since it is larger than the sum of its proper divisors (73855760).

81568516 is a wasteful number, since it uses less digits than its factorization.

81568516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1800 (or 1781 counting only the distinct ones).

The product of its digits is 57600, while the sum is 40.

The square root of 81568516 is about 9031.5289956906. The cubic root of 81568516 is about 433.6847860165.

It can be divided in two parts, 81 and 568516, that multiplied together give a square (46049796 = 6786²).

The spelling of 81568516 in words is "eighty-one million, five hundred sixty-eight thousand, five hundred sixteen".