2102021209 has 2 divisors, whose sum is σ = 2102021210. Its totient is φ = 2102021208.

The previous prime is 2102021189. The next prime is 2102021227. The reversal of 2102021209 is 9021202012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1105230025 + 996791184 = 33245^2 + 31572^2 .

It is a cyclic number.

It is not a de Polignac number, because 2102021209 - 2⁷ = 2102021081 is a prime.

It is not a weakly prime, because it can be changed into another prime (2102021249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1051010604 + 1051010605.

It is an arithmetic number, because the mean of its divisors is an integer number (1051010605).

Almost surely, 2^2102021209 is an apocalyptic number.

It is an amenable number.

2102021209 is a deficient number, since it is larger than the sum of its proper divisors (1).

2102021209 is an equidigital number, since it uses as much as digits as its factorization.

2102021209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 2102021209 is about 45847.8048438527. The cubic root of 2102021209 is about 1280.9898773963.

The spelling of 2102021209 in words is "two billion, one hundred two million, twenty-one thousand, two hundred nine".