2121200909 has 2 divisors, whose sum is σ = 2121200910. Its totient is φ = 2121200908.

The previous prime is 2121200903. The next prime is 2121200923. The reversal of 2121200909 is 9090021212.

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., 1801578025 + 319622884 = 42445^2 + 17878^2 .

It is a cyclic number.

It is not a de Polignac number, because 2121200909 - 2¹² = 2121196813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2121200903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1060600454 + 1060600455.

It is an arithmetic number, because the mean of its divisors is an integer number (1060600455).

Almost surely, 2^2121200909 is an apocalyptic number.

It is an amenable number.

2121200909 is a deficient number, since it is larger than the sum of its proper divisors (1).

2121200909 is an equidigital number, since it uses as much as digits as its factorization.

2121200909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 2121200909 is about 46056.4969249725. The cubic root of 2121200909 is about 1284.8741788619.

The spelling of 2121200909 in words is "two billion, one hundred twenty-one million, two hundred thousand, nine hundred nine".