1987890 has 64 divisors (see below), whose sum is σ = 5170176. Its totient is φ = 487872.

The previous prime is 1987889. The next prime is 1987891. The reversal of 1987890 is 987891.

It is an interprime number because it is at equal distance from previous prime (1987889) and next prime (1987891).

It is not an unprimeable number, because it can be changed into a prime (1987891) 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 31 ways as a sum of consecutive naturals, for example, 29637 + ... + 29703.

It is an arithmetic number, because the mean of its divisors is an integer number (80784).

2^1987890 is an apocalyptic number.

1987890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1987890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2585088).

1987890 is an abundant number, since it is smaller than the sum of its proper divisors (3182286).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1987890 is a wasteful number, since it uses less digits than its factorization.

1987890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143.

The product of its (nonzero) digits is 36288, while the sum is 42.

The square root of 1987890 is about 1409.9255299483. The cubic root of 1987890 is about 125.7372959405.

Subtracting from 1987890 its reverse (987891), we obtain a palindrome (999999).

The spelling of 1987890 in words is "one million, nine hundred eighty-seven thousand, eight hundred ninety".