1645232161 has 4 divisors (see below), whose sum is σ = 1645528852. Its totient is φ = 1644935472.

The previous prime is 1645232131. The next prime is 1645232179. The reversal of 1645232161 is 1612325461.

It is a happy number.

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 632019600 + 1013212561 = 25140^2 + 31831^2 .

It is a cyclic number.

It is not a de Polignac number, because 1645232161 - 2⁷ = 1645232033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1645232131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 139866 + ... + 151171.

It is an arithmetic number, because the mean of its divisors is an integer number (411382213).

Almost surely, 2^1645232161 is an apocalyptic number.

It is an amenable number.

1645232161 is a deficient number, since it is larger than the sum of its proper divisors (296691).

1645232161 is an equidigital number, since it uses as much as digits as its factorization.

1645232161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 296690.

The product of its digits is 8640, while the sum is 31.

The square root of 1645232161 is about 40561.4615244569. The cubic root of 1645232161 is about 1180.5264721971.

It can be divided in two parts, 164 and 5232161, that added together give a palindrome (5232325).

The spelling of 1645232161 in words is "one billion, six hundred forty-five million, two hundred thirty-two thousand, one hundred sixty-one".