990220818821 has 8 divisors (see below), whose sum is σ = 1095213047544. Its totient is φ = 889345932480.

The previous prime is 990220818799. The next prime is 990220818841. The reversal of 990220818821 is 128818022099.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 300100178596 + 690120640225 = 547814^2 + 830735^2 .

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 990220818821 - 2⁶ = 990220818757 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 990220818821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (990220818841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1029335090 + ... + 1029336051.

It is an arithmetic number, because the mean of its divisors is an integer number (136901630943).

Almost surely, 2^990220818821 is an apocalyptic number.

It is an amenable number.

990220818821 is a deficient number, since it is larger than the sum of its proper divisors (104992228723).

990220818821 is a wasteful number, since it uses less digits than its factorization.

990220818821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2058671191.

The product of its (nonzero) digits is 331776, while the sum is 50.

The spelling of 990220818821 in words is "nine hundred ninety billion, two hundred twenty million, eight hundred eighteen thousand, eight hundred twenty-one".