81561059 has 4 divisors (see below), whose sum is σ = 85107216. Its totient is φ = 78014904.

The previous prime is 81561049. The next prime is 81561089. The reversal of 81561059 is 95016518.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81561059 - 2¹² = 81556963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81561049) 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, 1773044 + ... + 1773089.

It is an arithmetic number, because the mean of its divisors is an integer number (21276804).

Almost surely, 2^81561059 is an apocalyptic number.

81561059 is a deficient number, since it is larger than the sum of its proper divisors (3546157).

81561059 is a wasteful number, since it uses less digits than its factorization.

81561059 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3546156.

The product of its (nonzero) digits is 10800, while the sum is 35.

The square root of 81561059 is about 9031.1161547175. The cubic root of 81561059 is about 433.6715697816.

The spelling of 81561059 in words is "eighty-one million, five hundred sixty-one thousand, fifty-nine".