1020021209 has 2 divisors, whose sum is σ = 1020021210. Its totient is φ = 1020021208.

The previous prime is 1020021187. The next prime is 1020021229. The reversal of 1020021209 is 9021200201.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 683665609 + 336355600 = 26147^2 + 18340^2 .

It is a cyclic number.

It is not a de Polignac number, because 1020021209 - 2¹² = 1020017113 is a prime.

It is not a weakly prime, because it can be changed into another prime (1020021229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 510010604 + 510010605.

It is an arithmetic number, because the mean of its divisors is an integer number (510010605).

Almost surely, 2^1020021209 is an apocalyptic number.

It is an amenable number.

1020021209 is a deficient number, since it is larger than the sum of its proper divisors (1).

1020021209 is an equidigital number, since it uses as much as digits as its factorization.

1020021209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 1020021209 is about 31937.7708833913. The cubic root of 1020021209 is about 1006.6296864598.

The spelling of 1020021209 in words is "one billion, twenty million, twenty-one thousand, two hundred nine".