81077540 has 24 divisors (see below), whose sum is σ = 173056632. Its totient is φ = 31898880.

The previous prime is 81077537. The next prime is 81077543. The reversal of 81077540 is 4577018.

It is an interprime number because it is at equal distance from previous prime (81077537) and next prime (81077543).

It can be written as a sum of positive squares in 4 ways, for example, as 1653796 + 79423744 = 1286^2 + 8912^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81077497 and 81077506.

It is not an unprimeable number, because it can be changed into a prime (81077543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32009 + ... + 34448.

It is an arithmetic number, because the mean of its divisors is an integer number (7210693).

Almost surely, 2^81077540 is an apocalyptic number.

It is an amenable number.

81077540 is an abundant number, since it is smaller than the sum of its proper divisors (91979092).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81077540 is a wasteful number, since it uses less digits than its factorization.

81077540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66527 (or 66525 counting only the distinct ones).

The product of its (nonzero) digits is 7840, while the sum is 32.

The square root of 81077540 is about 9004.3067473293. The cubic root of 81077540 is about 432.8128912967.

The spelling of 81077540 in words is "eighty-one million, seventy-seven thousand, five hundred forty".