204420521 has 2 divisors, whose sum is σ = 204420522. Its totient is φ = 204420520.

The previous prime is 204420509. The next prime is 204420569. The reversal of 204420521 is 125024402.

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., 172554496 + 31866025 = 13136^2 + 5645^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-204420521 is a prime.

It is a super-2 number, since 2×204420521² = 83575498811822882, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 204420493 and 204420502.

It is not a weakly prime, because it can be changed into another prime (204420421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102210260 + 102210261.

It is an arithmetic number, because the mean of its divisors is an integer number (102210261).

Almost surely, 2^204420521 is an apocalyptic number.

It is an amenable number.

204420521 is a deficient number, since it is larger than the sum of its proper divisors (1).

204420521 is an equidigital number, since it uses as much as digits as its factorization.

204420521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 640, while the sum is 20.

The square root of 204420521 is about 14297.5704579484. The cubic root of 204420521 is about 589.0807489101.

Adding to 204420521 its reverse (125024402), we get a palindrome (329444923).

The spelling of 204420521 in words is "two hundred four million, four hundred twenty thousand, five hundred twenty-one".