1581881 has 4 divisors (see below), whose sum is σ = 1807872. Its totient is φ = 1355892.

The previous prime is 1581869. The next prime is 1581889. The reversal of 1581881 is 1881851.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1581881 - 2¹⁸ = 1319737 is a prime.

It is a super-2 number, since 2×1581881² = 5004694996322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1581889) 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, 112985 + ... + 112998.

It is an arithmetic number, because the mean of its divisors is an integer number (451968).

2^1581881 is an apocalyptic number.

It is an amenable number.

1581881 is a deficient number, since it is larger than the sum of its proper divisors (225991).

1581881 is an equidigital number, since it uses as much as digits as its factorization.

1581881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 225990.

The product of its digits is 2560, while the sum is 32.

The square root of 1581881 is about 1257.7285080652. The cubic root of 1581881 is about 116.5175300728.

The spelling of 1581881 in words is "one million, five hundred eighty-one thousand, eight hundred eighty-one".