1988861 has 12 divisors (see below), whose sum is σ = 2378268.
Its totient is φ = 1657152.
The previous prime is 1988851. The next prime is 1988887. The reversal of 1988861 is 1688891.
It can be written as a sum of positive squares in 2 ways, for example, as 1223236 + 765625 = 1106^2 + 875^2
It is not a de Polignac number, because 1988861 - 26 = 1988797 is a prime.
It is a Smith number, since the sum of its digits (41) coincides with the sum of the digits of its prime factors.
1988861 is a strobogrammatic number because it is the same when read upside-down.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (1988801) by changing a digit.
It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1265 + ... + 2361.
It is an arithmetic number, because the mean of its divisors is an integer number (198189).
21988861 is an apocalyptic number.
It is an amenable number.
1988861 is a deficient number, since it is larger than the sum of its proper divisors (389407).
1988861 is a wasteful number, since it uses less digits than its factorization.
1988861 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 1148 (or 1141 counting only the distinct ones).
The product of its digits is 27648, while the sum is 41.
The square root of 1988861 is about 1410.2698323371.
The cubic root of 1988861 is about 125.7577650545.
The spelling of 1988861 in words is "one million, nine hundred eighty-eight thousand, eight hundred sixty-one".