81510205 has 32 divisors (see below), whose sum is σ = 114462720. Its totient is φ = 54574080.

The previous prime is 81510203. The next prime is 81510227. The reversal of 81510205 is 50201518.

It is not a de Polignac number, because 81510205 - 2¹ = 81510203 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81510203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 426660 + ... + 426850.

It is an arithmetic number, because the mean of its divisors is an integer number (3576960).

Almost surely, 2^81510205 is an apocalyptic number.

It is an amenable number.

81510205 is a deficient number, since it is larger than the sum of its proper divisors (32952515).

81510205 is a wasteful number, since it uses less digits than its factorization.

81510205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 429.

The product of its (nonzero) digits is 400, while the sum is 22.

The square root of 81510205 is about 9028.3002276176. The cubic root of 81510205 is about 433.5814184297.

It can be divided in two parts, 8151020 and 5, that added together give a square (8151025 = 2855²).

The spelling of 81510205 in words is "eighty-one million, five hundred ten thousand, two hundred five".