1644320161 has 8 divisors (see below), whose sum is σ = 1798804800. Its totient is φ = 1490669040.

The previous prime is 1644320143. The next prime is 1644320179. The reversal of 1644320161 is 1610234461.

It is an interprime number because it is at equal distance from previous prime (1644320143) and next prime (1644320179).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1644320161 - 2⁷ = 1644320033 is a prime.

It is a super-3 number, since 3×1644320161³ (a number of 29 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1644320101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 204246 + ... + 212143.

It is an arithmetic number, because the mean of its divisors is an integer number (224850600).

Almost surely, 2^1644320161 is an apocalyptic number.

1644320161 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1644320161 is a deficient number, since it is larger than the sum of its proper divisors (154484639).

1644320161 is a wasteful number, since it uses less digits than its factorization.

1644320161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 416759.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 1644320161 is about 40550.2177676027. The cubic root of 1644320161 is about 1180.3082985016.

The spelling of 1644320161 in words is "one billion, six hundred forty-four million, three hundred twenty thousand, one hundred sixty-one".