1987129 has 4 divisors (see below), whose sum is σ = 2024676. Its totient is φ = 1949584.

The previous prime is 1987127. The next prime is 1987151. The reversal of 1987129 is 9217891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9217891 = 1657 ⋅5563.

It can be written as a sum of positive squares in 2 ways, for example, as 946729 + 1040400 = 973^2 + 1020^2 .

It is a cyclic number.

It is not a de Polignac number, because 1987129 - 2¹ = 1987127 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1987121) 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, 18694 + ... + 18799.

It is an arithmetic number, because the mean of its divisors is an integer number (506169).

2^1987129 is an apocalyptic number.

It is an amenable number.

1987129 is a deficient number, since it is larger than the sum of its proper divisors (37547).

1987129 is an equidigital number, since it uses as much as digits as its factorization.

1987129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37546.

The product of its digits is 9072, while the sum is 37.

The square root of 1987129 is about 1409.6556317058. The cubic root of 1987129 is about 125.7212490609.

It can be divided in two parts, 19871 and 29, that added together give a triangular number (19900 = T₁₉₉).

The spelling of 1987129 in words is "one million, nine hundred eighty-seven thousand, one hundred twenty-nine".