1204020821 has 2 divisors, whose sum is σ = 1204020822. Its totient is φ = 1204020820.

The previous prime is 1204020799. The next prime is 1204020827. The reversal of 1204020821 is 1280204021.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 812535025 + 391485796 = 28505^2 + 19786^2 .

It is a cyclic number.

It is not a de Polignac number, because 1204020821 - 2⁶ = 1204020757 is a prime.

It is a super-2 number, since 2×1204020821² = 2899332274803028082, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1204020793 and 1204020802.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1204020827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 602010410 + 602010411.

It is an arithmetic number, because the mean of its divisors is an integer number (602010411).

Almost surely, 2^1204020821 is an apocalyptic number.

It is an amenable number.

1204020821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1204020821 is an equidigital number, since it uses as much as digits as its factorization.

1204020821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 1204020821 is about 34699.0031701200. The cubic root of 1204020821 is about 1063.8441237747.

Adding to 1204020821 its reverse (1280204021), we get a palindrome (2484224842).

The spelling of 1204020821 in words is "one billion, two hundred four million, twenty thousand, eight hundred twenty-one".