81405015 has 16 divisors (see below), whose sum is σ = 131445600. Its totient is φ = 43016832.

The previous prime is 81405013. The next prime is 81405029. The reversal of 81405015 is 51050418.

It is not a de Polignac number, because 81405015 - 2¹ = 81405013 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81405011) 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 15 ways as a sum of consecutive naturals, for example, 23260 + ... + 26529.

It is an arithmetic number, because the mean of its divisors is an integer number (8215350).

Almost surely, 2^81405015 is an apocalyptic number.

81405015 is a deficient number, since it is larger than the sum of its proper divisors (50040585).

81405015 is a wasteful number, since it uses less digits than its factorization.

81405015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49906.

The product of its (nonzero) digits is 800, while the sum is 24.

The square root of 81405015 is about 9022.4727763513. The cubic root of 81405015 is about 433.3948239499.

The spelling of 81405015 in words is "eighty-one million, four hundred five thousand, fifteen".