81561083 has 4 divisors (see below), whose sum is σ = 81736200. Its totient is φ = 81385968.

The previous prime is 81561049. The next prime is 81561089. The reversal of 81561083 is 38016518.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 38016518 = 2 ⋅19008259.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81561083 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81561089) 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, 86858 + ... + 87791.

It is an arithmetic number, because the mean of its divisors is an integer number (20434050).

Almost surely, 2^81561083 is an apocalyptic number.

81561083 is a deficient number, since it is larger than the sum of its proper divisors (175117).

81561083 is a wasteful number, since it uses less digits than its factorization.

81561083 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175116.

The product of its (nonzero) digits is 5760, while the sum is 32.

The square root of 81561083 is about 9031.1174834569. The cubic root of 81561083 is about 433.6716123187.

The spelling of 81561083 in words is "eighty-one million, five hundred sixty-one thousand, eighty-three".