81123775 has 6 divisors (see below), whose sum is σ = 100593512. Its totient is φ = 64899000.

The previous prime is 81123773. The next prime is 81123811. The reversal of 81123775 is 57732118.

It is not a de Polignac number, because 81123775 - 2¹ = 81123773 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81123775.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81123773) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1622451 + ... + 1622500.

Almost surely, 2^81123775 is an apocalyptic number.

81123775 is a deficient number, since it is larger than the sum of its proper divisors (19469737).

81123775 is a wasteful number, since it uses less digits than its factorization.

81123775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3244961 (or 3244956 counting only the distinct ones).

The product of its digits is 11760, while the sum is 34.

The square root of 81123775 is about 9006.8737639649. The cubic root of 81123775 is about 432.8951471282.

The spelling of 81123775 in words is "eighty-one million, one hundred twenty-three thousand, seven hundred seventy-five".