1987881 has 12 divisors (see below), whose sum is σ = 3083472. Its totient is φ = 1135848.

The previous prime is 1987879. The next prime is 1987883. The reversal of 1987881 is 1887891.

It is an interprime number because it is at equal distance from previous prime (1987879) and next prime (1987883).

It is not a de Polignac number, because 1987881 - 2¹ = 1987879 is a prime.

It is a super-2 number, since 2×1987881² = 7903341740322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1987883) 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 11 ways as a sum of consecutive naturals, for example, 6615 + ... + 6908.

It is an arithmetic number, because the mean of its divisors is an integer number (256956).

2^1987881 is an apocalyptic number.

It is an amenable number.

1987881 is a deficient number, since it is larger than the sum of its proper divisors (1095591).

1987881 is a wasteful number, since it uses less digits than its factorization.

1987881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13540 (or 13533 counting only the distinct ones).

The product of its digits is 32256, while the sum is 42.

The square root of 1987881 is about 1409.9223382868. The cubic root of 1987881 is about 125.7371061853.

The spelling of 1987881 in words is "one million, nine hundred eighty-seven thousand, eight hundred eighty-one".