81561683 has 8 divisors (see below), whose sum is σ = 94119168. Its totient is φ = 69230664.

The previous prime is 81561679. The next prime is 81561691. The reversal of 81561683 is 38616518.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81561683 - 2² = 81561679 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81564683) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 55841 + ... + 57282.

It is an arithmetic number, because the mean of its divisors is an integer number (11764896).

Almost surely, 2^81561683 is an apocalyptic number.

81561683 is a deficient number, since it is larger than the sum of its proper divisors (12557485).

81561683 is a wasteful number, since it uses less digits than its factorization.

81561683 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113233.

The product of its digits is 34560, while the sum is 38.

The square root of 81561683 is about 9031.1507018763. The cubic root of 81561683 is about 433.6726757439.

The spelling of 81561683 in words is "eighty-one million, five hundred sixty-one thousand, six hundred eighty-three".