81148765 has 4 divisors (see below), whose sum is σ = 97378524. Its totient is φ = 64919008.

The previous prime is 81148741. The next prime is 81148787. The reversal of 81148765 is 56784118.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 48818169 + 32330596 = 6987^2 + 5686^2 .

It is a cyclic number.

It is not a de Polignac number, because 81148765 - 2⁷ = 81148637 is a prime.

It is a super-2 number, since 2×81148765² = 13170244122050450, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8114872 + ... + 8114881.

It is an arithmetic number, because the mean of its divisors is an integer number (24344631).

Almost surely, 2^81148765 is an apocalyptic number.

It is an amenable number.

81148765 is a deficient number, since it is larger than the sum of its proper divisors (16229759).

81148765 is a wasteful number, since it uses less digits than its factorization.

81148765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16229758.

The product of its digits is 53760, while the sum is 40.

The square root of 81148765 is about 9008.2609309456. The cubic root of 81148765 is about 432.9395933632.

The spelling of 81148765 in words is "eighty-one million, one hundred forty-eight thousand, seven hundred sixty-five".