1581887 has 4 divisors (see below), whose sum is σ = 1596000. Its totient is φ = 1567776.

The previous prime is 1581869. The next prime is 1581889. The reversal of 1581887 is 7881851.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7881851 = 37 ⋅213023.

It is a cyclic number.

It is not a de Polignac number, because 1581887 - 2¹⁸ = 1319743 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1581887.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1581889) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6887 + ... + 7112.

It is an arithmetic number, because the mean of its divisors is an integer number (399000).

2^1581887 is an apocalyptic number.

1581887 is a deficient number, since it is larger than the sum of its proper divisors (14113).

1581887 is a wasteful number, since it uses less digits than its factorization.

1581887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14112.

The product of its digits is 17920, while the sum is 38.

The square root of 1581887 is about 1257.7308933154. The cubic root of 1581887 is about 116.5176773878.

The spelling of 1581887 in words is "one million, five hundred eighty-one thousand, eight hundred eighty-seven".