81121766 has 16 divisors (see below), whose sum is σ = 132889680. Its totient is φ = 36833280.

The previous prime is 81121757. The next prime is 81121769. The reversal of 81121766 is 66712118.

It is a happy number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81121769) 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, 29690 + ... + 32306.

It is an arithmetic number, because the mean of its divisors is an integer number (8305605).

Almost surely, 2^81121766 is an apocalyptic number.

81121766 is a deficient number, since it is larger than the sum of its proper divisors (51767914).

81121766 is a wasteful number, since it uses less digits than its factorization.

81121766 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4039.

The product of its digits is 4032, while the sum is 32.

The square root of 81121766 is about 9006.7622373415. The cubic root of 81121766 is about 432.8915736032.

The spelling of 81121766 in words is "eighty-one million, one hundred twenty-one thousand, seven hundred sixty-six".