8161581 has 8 divisors (see below), whose sum is σ = 11522304. Its totient is φ = 5120960.

The previous prime is 8161579. The next prime is 8161589. The reversal of 8161581 is 1851618.

It is a happy number.

8161581 is digitally balanced in base 3 and base 4, because in such bases it contains all the possibile digits an equal number of times.

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 8161581 - 2¹ = 8161579 is a prime.

It is a super-2 number, since 2×8161581² = 133222808839122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8161589) 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, 79965 + ... + 80066.

It is an arithmetic number, because the mean of its divisors is an integer number (1440288).

Almost surely, 2^8161581 is an apocalyptic number.

It is an amenable number.

8161581 is a deficient number, since it is larger than the sum of its proper divisors (3360723).

8161581 is a wasteful number, since it uses less digits than its factorization.

8161581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160051.

The product of its digits is 1920, while the sum is 30.

The square root of 8161581 is about 2856.8480883659. The cubic root of 8161581 is about 201.3375432824.

It can be divided in two parts, 81 and 61581, that multiplied together give a triangular number (4988061 = T₃₁₅₈).

The spelling of 8161581 in words is "eight million, one hundred sixty-one thousand, five hundred eighty-one".