1646009021 has 2 divisors, whose sum is σ = 1646009022. Its totient is φ = 1646009020.

The previous prime is 1646009017. The next prime is 1646009039. The reversal of 1646009021 is 1209006461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1173816121 + 472192900 = 34261^2 + 21730^2 .

It is a cyclic number.

It is not a de Polignac number, because 1646009021 - 2² = 1646009017 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1646009011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 823004510 + 823004511.

It is an arithmetic number, because the mean of its divisors is an integer number (823004511).

Almost surely, 2^1646009021 is an apocalyptic number.

It is an amenable number.

1646009021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1646009021 is an equidigital number, since it uses as much as digits as its factorization.

1646009021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 1646009021 is about 40571.0367257234. The cubic root of 1646009021 is about 1180.7122533705.

The spelling of 1646009021 in words is "one billion, six hundred forty-six million, nine thousand, twenty-one".