81391550745 has 16 divisors (see below), whose sum is σ = 134427336192. Its totient is φ = 42008542080.

The previous prime is 81391550741. The next prime is 81391550753. The reversal of 81391550745 is 54705519318.

It is not a de Polignac number, because 81391550745 - 2² = 81391550741 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81391550694 and 81391550703.

It is not an unprimeable number, because it can be changed into a prime (81391550741) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 87517332 + ... + 87518261.

It is an arithmetic number, because the mean of its divisors is an integer number (8401708512).

Almost surely, 2^81391550745 is an apocalyptic number.

It is an amenable number.

81391550745 is a deficient number, since it is larger than the sum of its proper divisors (53035785447).

81391550745 is a wasteful number, since it uses less digits than its factorization.

81391550745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175035632.

The product of its (nonzero) digits is 756000, while the sum is 48.

The spelling of 81391550745 in words is "eighty-one billion, three hundred ninety-one million, five hundred fifty thousand, seven hundred forty-five".