1581861 has 8 divisors (see below), whose sum is σ = 2166304. Its totient is φ = 1026000.

The previous prime is 1581859. The next prime is 1581869. The reversal of 1581861 is 1681851.

It is a happy number.

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

It is not a de Polignac number, because 1581861 - 2¹ = 1581859 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1581869) 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, 7015 + ... + 7236.

It is an arithmetic number, because the mean of its divisors is an integer number (270788).

2^1581861 is an apocalyptic number.

It is an amenable number.

1581861 is a deficient number, since it is larger than the sum of its proper divisors (584443).

1581861 is a wasteful number, since it uses less digits than its factorization.

1581861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14291.

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

The square root of 1581861 is about 1257.7205571986. The cubic root of 1581861 is about 116.5170390202.

It can be divided in two parts, 1581 and 861, that added together give a palindrome (2442).

The spelling of 1581861 in words is "one million, five hundred eighty-one thousand, eight hundred sixty-one".