81138277 has 4 divisors (see below), whose sum is σ = 88514496. Its totient is φ = 73762060.

The previous prime is 81138271. The next prime is 81138287. The reversal of 81138277 is 77283118.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81138277 - 2⁷ = 81138149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81138271) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3688093 + ... + 3688114.

It is an arithmetic number, because the mean of its divisors is an integer number (22128624).

Almost surely, 2^81138277 is an apocalyptic number.

It is an amenable number.

81138277 is a deficient number, since it is larger than the sum of its proper divisors (7376219).

81138277 is a wasteful number, since it uses less digits than its factorization.

81138277 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7376218.

The product of its digits is 18816, while the sum is 37.

The square root of 81138277 is about 9007.6787797967. The cubic root of 81138277 is about 432.9209409286.

The spelling of 81138277 in words is "eighty-one million, one hundred thirty-eight thousand, two hundred seventy-seven".