81246721766 has 16 divisors (see below), whose sum is σ = 139295033856. Its totient is φ = 34816288776.

The previous prime is 81246721763. The next prime is 81246721771. The reversal of 81246721766 is 66712764218.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81246721763) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 173966 + ... + 439041.

It is an arithmetic number, because the mean of its divisors is an integer number (8705939616).

Almost surely, 2^81246721766 is an apocalyptic number.

81246721766 is a deficient number, since it is larger than the sum of its proper divisors (58048312090).

81246721766 is a wasteful number, since it uses less digits than its factorization.

81246721766 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 622483.

The product of its digits is 1354752, while the sum is 50.

The spelling of 81246721766 in words is "eighty-one billion, two hundred forty-six million, seven hundred twenty-one thousand, seven hundred sixty-six".