1988139 has 4 divisors (see below), whose sum is σ = 2650856. Its totient is φ = 1325424.

The previous prime is 1988137. The next prime is 1988177. The reversal of 1988139 is 9318891.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9318891 = 3 ⋅3106297.

It is not a de Polignac number, because 1988139 - 2¹ = 1988137 is a prime.

It is a D-number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1988097 and 1988106.

It is not an unprimeable number, because it can be changed into a prime (1988137) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 331354 + ... + 331359.

It is an arithmetic number, because the mean of its divisors is an integer number (662714).

2^1988139 is an apocalyptic number.

1988139 is a deficient number, since it is larger than the sum of its proper divisors (662717).

1988139 is an equidigital number, since it uses as much as digits as its factorization.

1988139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 662716.

The product of its digits is 15552, while the sum is 39.

The square root of 1988139 is about 1410.0138297194. The cubic root of 1988139 is about 125.7425456072.

Subtracting from 1988139 its sum of digits (39), we obtain a square (1988100 = 1410²).

The spelling of 1988139 in words is "one million, nine hundred eighty-eight thousand, one hundred thirty-nine".