81545815 has 16 divisors (see below), whose sum is σ = 110930400. Its totient is φ = 57048192.

The previous prime is 81545813. The next prime is 81545831. The reversal of 81545815 is 51854518.

It is a cyclic number.

It is not a de Polignac number, because 81545815 - 2¹ = 81545813 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81545813) 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, 31780 + ... + 34249.

It is an arithmetic number, because the mean of its divisors is an integer number (6933150).

Almost surely, 2^81545815 is an apocalyptic number.

81545815 is a deficient number, since it is larger than the sum of its proper divisors (29384585).

81545815 is a wasteful number, since it uses less digits than its factorization.

81545815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66066.

The product of its digits is 32000, while the sum is 37.

The square root of 81545815 is about 9030.2721442933. The cubic root of 81545815 is about 433.6445499374.

The spelling of 81545815 in words is "eighty-one million, five hundred forty-five thousand, eight hundred fifteen".