1998224821 has 2 divisors, whose sum is σ = 1998224822. Its totient is φ = 1998224820.

The previous prime is 1998224807. The next prime is 1998224861. The reversal of 1998224821 is 1284228991.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1134746596 + 863478225 = 33686^2 + 29385^2 .

It is a cyclic number.

It is not a de Polignac number, because 1998224821 - 2¹⁷ = 1998093749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1998224861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999112410 + 999112411.

It is an arithmetic number, because the mean of its divisors is an integer number (999112411).

Almost surely, 2^1998224821 is an apocalyptic number.

It is an amenable number.

1998224821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1998224821 is an equidigital number, since it uses as much as digits as its factorization.

1998224821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 165888, while the sum is 46.

The square root of 1998224821 is about 44701.5080394387. The cubic root of 1998224821 is about 1259.5481753217.

The spelling of 1998224821 in words is "one billion, nine hundred ninety-eight million, two hundred twenty-four thousand, eight hundred twenty-one".