81265761 has 12 divisors (see below), whose sum is σ = 121731792. Its totient is φ = 54177012.

The previous prime is 81265759. The next prime is 81265771. The reversal of 81265761 is 16756218.

81265761 is a `hidden beast` number, since 81 + 2 + 6 + 576 + 1 = 666.

It is not a de Polignac number, because 81265761 - 2¹ = 81265759 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81265721) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 166971 + ... + 167456.

It is an arithmetic number, because the mean of its divisors is an integer number (10144316).

Almost surely, 2^81265761 is an apocalyptic number.

81265761 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

81265761 is a deficient number, since it is larger than the sum of its proper divisors (40466031).

81265761 is an equidigital number, since it uses as much as digits as its factorization.

81265761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334442 (or 334430 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 81265761 is about 9014.7524092456. The cubic root of 81265761 is about 433.1475565922.

It can be divided in two parts, 81 and 265761, that multiplied together give a triangular number (21526641 = T₆₅₆₁).

The spelling of 81265761 in words is "eighty-one million, two hundred sixty-five thousand, seven hundred sixty-one".