1021021909 has 2 divisors, whose sum is σ = 1021021910. Its totient is φ = 1021021908.

The previous prime is 1021021901. The next prime is 1021021979. The reversal of 1021021909 is 9091201201.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 589421284 + 431600625 = 24278^2 + 20775^2 .

It is an emirp because it is prime and its reverse (9091201201) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1021021909 - 2³ = 1021021901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1021021901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 510510954 + 510510955.

It is an arithmetic number, because the mean of its divisors is an integer number (510510955).

Almost surely, 2^1021021909 is an apocalyptic number.

It is an amenable number.

1021021909 is a deficient number, since it is larger than the sum of its proper divisors (1).

1021021909 is an equidigital number, since it uses as much as digits as its factorization.

1021021909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 25.

The square root of 1021021909 is about 31953.4334461885. The cubic root of 1021021909 is about 1006.9587662476.

The spelling of 1021021909 in words is "one billion, twenty-one million, twenty-one thousand, nine hundred nine".