990621 has 6 divisors (see below), whose sum is σ = 1430910. Its totient is φ = 660408.

The previous prime is 990599. The next prime is 990631. The reversal of 990621 is 126099.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 881721 + 108900 = 939^2 + 330^2 .

It is not a de Polignac number, because 990621 - 2⁵ = 990589 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (990631) 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 5 ways as a sum of consecutive naturals, for example, 55026 + ... + 55043.

It is an arithmetic number, because the mean of its divisors is an integer number (238485).

2⁹⁹⁰⁶²¹ is an apocalyptic number.

It is an amenable number.

990621 is a deficient number, since it is larger than the sum of its proper divisors (440289).

990621 is a wasteful number, since it uses less digits than its factorization.

990621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110075 (or 110072 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 990621 is about 995.2994524263. The cubic root of 990621 is about 99.6863841458.

The spelling of 990621 in words is "nine hundred ninety thousand, six hundred twenty-one".