81306775 has 24 divisors (see below), whose sum is σ = 110492928. Its totient is φ = 58860000.

The previous prime is 81306737. The next prime is 81306781. The reversal of 81306775 is 57760318.

It is not a de Polignac number, because 81306775 - 2²¹ = 79209623 is a prime.

It is a super-2 number, since 2×81306775² = 13221583321801250, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 73980 + ... + 75070.

It is an arithmetic number, because the mean of its divisors is an integer number (4603872).

Almost surely, 2^81306775 is an apocalyptic number.

81306775 is a deficient number, since it is larger than the sum of its proper divisors (29186153).

81306775 is a wasteful number, since it uses less digits than its factorization.

81306775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1383 (or 1378 counting only the distinct ones).

The product of its (nonzero) digits is 35280, while the sum is 37.

The square root of 81306775 is about 9017.0269490559. The cubic root of 81306775 is about 433.2204127203.

The spelling of 81306775 in words is "eighty-one million, three hundred six thousand, seven hundred seventy-five".