8261581 has 4 divisors (see below), whose sum is σ = 8279964. Its totient is φ = 8243200.

The previous prime is 8261573. The next prime is 8261621. The reversal of 8261581 is 1851628.

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 1020100 + 7241481 = 1010^2 + 2691^2 .

It is a cyclic number.

It is not a de Polignac number, because 8261581 - 2³ = 8261573 is a prime.

It is a super-2 number, since 2×8261581² = 136507441239122, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8261501) 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, 8500 + ... + 9421.

It is an arithmetic number, because the mean of its divisors is an integer number (2069991).

Almost surely, 2^8261581 is an apocalyptic number.

It is an amenable number.

8261581 is a deficient number, since it is larger than the sum of its proper divisors (18383).

8261581 is a wasteful number, since it uses less digits than its factorization.

8261581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18382.

The product of its digits is 3840, while the sum is 31.

The square root of 8261581 is about 2874.2966096073. The cubic root of 8261581 is about 202.1565055127.

The spelling of 8261581 in words is "eight million, two hundred sixty-one thousand, five hundred eighty-one".