1020191021 has 2 divisors, whose sum is σ = 1020191022. Its totient is φ = 1020191020.

The previous prime is 1020191017. The next prime is 1020191057. The reversal of 1020191021 is 1201910201.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 548215396 + 471975625 = 23414^2 + 21725^2 .

It is a cyclic number.

It is not a de Polignac number, because 1020191021 - 2² = 1020191017 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1020191321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 510095510 + 510095511.

It is an arithmetic number, because the mean of its divisors is an integer number (510095511).

Almost surely, 2^1020191021 is an apocalyptic number.

It is an amenable number.

1020191021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1020191021 is an equidigital number, since it uses as much as digits as its factorization.

1020191021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36, while the sum is 17.

The square root of 1020191021 is about 31940.4292550992. The cubic root of 1020191021 is about 1006.6855442249.

The spelling of 1020191021 in words is "one billion, twenty million, one hundred ninety-one thousand, twenty-one".