81447817515 has 16 divisors (see below), whose sum is σ = 131311293696. Its totient is φ = 43107240800.

The previous prime is 81447817501. The next prime is 81447817519. The reversal of 81447817515 is 51571874418.

It is not a de Polignac number, because 81447817515 - 2¹⁰ = 81447816491 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81447817519) 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 15 ways as a sum of consecutive naturals, for example, 20722671 + ... + 20726600.

It is an arithmetic number, because the mean of its divisors is an integer number (8206955856).

Almost surely, 2^81447817515 is an apocalyptic number.

81447817515 is a deficient number, since it is larger than the sum of its proper divisors (49863476181).

81447817515 is a wasteful number, since it uses less digits than its factorization.

81447817515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41449410.

The product of its digits is 1254400, while the sum is 51.

The spelling of 81447817515 in words is "eighty-one billion, four hundred forty-seven million, eight hundred seventeen thousand, five hundred fifteen".