81766516309215 has 32 divisors (see below), whose sum is σ = 135666763654656. Its totient is φ = 42018248603520.

The previous prime is 81766516309211. The next prime is 81766516309223. The reversal of 81766516309215 is 51290361566718.

It is a happy number.

It is not a de Polignac number, because 81766516309215 - 2² = 81766516309211 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81766516309211) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 715122721 + ... + 715237050.

It is an arithmetic number, because the mean of its divisors is an integer number (4239586364208).

Almost surely, 2^{81766516309215} is an apocalyptic number.

81766516309215 is a deficient number, since it is larger than the sum of its proper divisors (53900247345441).

81766516309215 is a wasteful number, since it uses less digits than its factorization.

81766516309215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1430359919.

The product of its (nonzero) digits is 16329600, while the sum is 60.

The spelling of 81766516309215 in words is "eighty-one trillion, seven hundred sixty-six billion, five hundred sixteen million, three hundred nine thousand, two hundred fifteen".