1990551 has 4 divisors (see below), whose sum is σ = 2654072. Its totient is φ = 1327032.

The previous prime is 1990543. The next prime is 1990553. The reversal of 1990551 is 1550991.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1990551 - 2³ = 1990543 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1990553) 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, 331756 + ... + 331761.

It is an arithmetic number, because the mean of its divisors is an integer number (663518).

2^1990551 is an apocalyptic number.

1990551 is a deficient number, since it is larger than the sum of its proper divisors (663521).

1990551 is an equidigital number, since it uses as much as digits as its factorization.

1990551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 663520.

The product of its (nonzero) digits is 2025, while the sum is 30.

The square root of 1990551 is about 1410.8688812218. The cubic root of 1990551 is about 125.7933751270.

The spelling of 1990551 in words is "one million, nine hundred ninety thousand, five hundred fifty-one".