1646811121 has 4 divisors (see below), whose sum is σ = 1647037044. Its totient is φ = 1646585200.

The previous prime is 1646811113. The next prime is 1646811137. The reversal of 1646811121 is 1211186461.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 981944896 + 664866225 = 31336^2 + 25785^2 .

It is a cyclic number.

It is not a de Polignac number, because 1646811121 - 2³ = 1646811113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1646811181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 101650 + ... + 116731.

It is an arithmetic number, because the mean of its divisors is an integer number (411759261).

Almost surely, 2^1646811121 is an apocalyptic number.

It is an amenable number.

1646811121 is a deficient number, since it is larger than the sum of its proper divisors (225923).

1646811121 is an equidigital number, since it uses as much as digits as its factorization.

1646811121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 225922.

The product of its digits is 2304, while the sum is 31.

The square root of 1646811121 is about 40580.9206524445. The cubic root of 1646811121 is about 1180.9040092066.

Adding to 1646811121 its reverse (1211186461), we get a palindrome (2857997582).

The spelling of 1646811121 in words is "one billion, six hundred forty-six million, eight hundred eleven thousand, one hundred twenty-one".