990551 has 8 divisors (see below), whose sum is σ = 1023360. Its totient is φ = 958392.

The previous prime is 990547. The next prime is 990559. The reversal of 990551 is 155099.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 990551 - 2² = 990547 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (990559) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5996 + ... + 6158.

It is an arithmetic number, because the mean of its divisors is an integer number (127920).

2⁹⁹⁰⁵⁵¹ is an apocalyptic number.

990551 is a deficient number, since it is larger than the sum of its proper divisors (32809).

990551 is a wasteful number, since it uses less digits than its factorization.

990551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 325.

The product of its (nonzero) digits is 2025, while the sum is 29.

The square root of 990551 is about 995.2642865089. The cubic root of 990551 is about 99.6840360526.

It can be divided in two parts, 990 and 551, that multiplied together give a triangular number (545490 = T₁₀₄₄).

The spelling of 990551 in words is "nine hundred ninety thousand, five hundred fifty-one".