1987561 has 8 divisors (see below), whose sum is σ = 2038400. Its totient is φ = 1937520.

The previous prime is 1987549. The next prime is 1987577. The reversal of 1987561 is 1657891.

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 1987561 - 2⁹ = 1987049 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 1987561.

It is not an unprimeable number, because it can be changed into a prime (1987501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10891 + ... + 11071.

It is an arithmetic number, because the mean of its divisors is an integer number (254800).

2^1987561 is an apocalyptic number.

It is an amenable number.

1987561 is a deficient number, since it is larger than the sum of its proper divisors (50839).

1987561 is a wasteful number, since it uses less digits than its factorization.

1987561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399.

The product of its digits is 15120, while the sum is 37.

The square root of 1987561 is about 1409.8088522917. The cubic root of 1987561 is about 125.7303589617.

The spelling of 1987561 in words is "one million, nine hundred eighty-seven thousand, five hundred sixty-one".