1990387 has 4 divisors (see below), whose sum is σ = 2274736. Its totient is φ = 1706040.

The previous prime is 1990381. The next prime is 1990433. The reversal of 1990387 is 7830991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7830991 = 7 ⋅1118713.

It is not a de Polignac number, because 1990387 - 2³ = 1990379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1990381) 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, 142164 + ... + 142177.

It is an arithmetic number, because the mean of its divisors is an integer number (568684).

2^1990387 is an apocalyptic number.

1990387 is a deficient number, since it is larger than the sum of its proper divisors (284349).

1990387 is an equidigital number, since it uses as much as digits as its factorization.

1990387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 284348.

The product of its (nonzero) digits is 13608, while the sum is 37.

The square root of 1990387 is about 1410.8107598115. The cubic root of 1990387 is about 125.7899203583.

The spelling of 1990387 in words is "one million, nine hundred ninety thousand, three hundred eighty-seven".