1009091021 has 2 divisors, whose sum is σ = 1009091022. Its totient is φ = 1009091020.

The previous prime is 1009091003. The next prime is 1009091051. The reversal of 1009091021 is 1201909001.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 795522025 + 213568996 = 28205^2 + 14614^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1009091021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1009091051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 504545510 + 504545511.

It is an arithmetic number, because the mean of its divisors is an integer number (504545511).

Almost surely, 2^1009091021 is an apocalyptic number.

It is an amenable number.

1009091021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1009091021 is an equidigital number, since it uses as much as digits as its factorization.

1009091021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 162, while the sum is 23.

The square root of 1009091021 is about 31766.1930517335. The cubic root of 1009091021 is about 1003.0212034707.

The spelling of 1009091021 in words is "one billion, nine million, ninety-one thousand, twenty-one".