81140285 has 4 divisors (see below), whose sum is σ = 97368348. Its totient is φ = 64912224.

The previous prime is 81140263. The next prime is 81140329. The reversal of 81140285 is 58204118.

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 49477156 + 31663129 = 7034^2 + 5627^2 .

It is a cyclic number.

It is not a de Polignac number, because 81140285 - 2⁸ = 81140029 is a prime.

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, 8114024 + ... + 8114033.

It is an arithmetic number, because the mean of its divisors is an integer number (24342087).

Almost surely, 2^81140285 is an apocalyptic number.

It is an amenable number.

81140285 is a deficient number, since it is larger than the sum of its proper divisors (16228063).

81140285 is a wasteful number, since it uses less digits than its factorization.

81140285 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16228062.

The product of its (nonzero) digits is 2560, while the sum is 29.

The square root of 81140285 is about 9007.7902395649. The cubic root of 81140285 is about 432.9245121904.

The spelling of 81140285 in words is "eighty-one million, one hundred forty thousand, two hundred eighty-five".