1646331521 has 2 divisors, whose sum is σ = 1646331522. Its totient is φ = 1646331520.

The previous prime is 1646331517. The next prime is 1646331541. The reversal of 1646331521 is 1251336461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1597121296 + 49210225 = 39964^2 + 7015^2 .

It is a cyclic number.

It is not a de Polignac number, because 1646331521 - 2² = 1646331517 is a prime.

It is not a weakly prime, because it can be changed into another prime (1646331541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 823165760 + 823165761.

It is an arithmetic number, because the mean of its divisors is an integer number (823165761).

Almost surely, 2^1646331521 is an apocalyptic number.

It is an amenable number.

1646331521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1646331521 is an equidigital number, since it uses as much as digits as its factorization.

1646331521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 32.

The square root of 1646331521 is about 40575.0110412801. The cubic root of 1646331521 is about 1180.7893600431.

Adding to 1646331521 its reverse (1251336461), we get a palindrome (2897667982).

The spelling of 1646331521 in words is "one billion, six hundred forty-six million, three hundred thirty-one thousand, five hundred twenty-one".