81107765 has 8 divisors (see below), whose sum is σ = 103054680. Its totient is φ = 61069312.

The previous prime is 81107753. The next prime is 81107771. The reversal of 81107765 is 56770118.

It can be written as a sum of positive squares in 4 ways, for example, as 21771556 + 59336209 = 4666^2 + 7703^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81107765 - 2⁶ = 81107701 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 477020 + ... + 477189.

It is an arithmetic number, because the mean of its divisors is an integer number (12881835).

Almost surely, 2^81107765 is an apocalyptic number.

81107765 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81107765 is a deficient number, since it is larger than the sum of its proper divisors (21946915).

81107765 is a wasteful number, since it uses less digits than its factorization.

81107765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 954231.

The product of its (nonzero) digits is 11760, while the sum is 35.

The square root of 81107765 is about 9005.9849544622. The cubic root of 81107765 is about 432.8666675722.

The spelling of 81107765 in words is "eighty-one million, one hundred seven thousand, seven hundred sixty-five".