81505064 has 8 divisors (see below), whose sum is σ = 152822010. Its totient is φ = 40752528.

The previous prime is 81505037. The next prime is 81505069. The reversal of 81505064 is 46050518.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 46812964 + 34692100 = 6842^2 + 5890^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (81505069) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5094059 + ... + 5094074.

Almost surely, 2^81505064 is an apocalyptic number.

It is an amenable number.

81505064 is a deficient number, since it is larger than the sum of its proper divisors (71316946).

81505064 is a wasteful number, since it uses less digits than its factorization.

81505064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10188139 (or 10188135 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 29.

The square root of 81505064 is about 9028.0155072973. The cubic root of 81505064 is about 433.5723026430.

The spelling of 81505064 in words is "eighty-one million, five hundred five thousand, sixty-four".