644161335 has 16 divisors (see below), whose sum is σ = 1040865120. Its totient is φ = 340150400.

The previous prime is 644161327. The next prime is 644161337. The reversal of 644161335 is 533161446.

It is not a de Polignac number, because 644161335 - 2³ = 644161327 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644161296 and 644161305.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644161337) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 211080 + ... + 214109.

It is an arithmetic number, because the mean of its divisors is an integer number (65054070).

Almost surely, 2^644161335 is an apocalyptic number.

644161335 is a deficient number, since it is larger than the sum of its proper divisors (396703785).

644161335 is a wasteful number, since it uses less digits than its factorization.

644161335 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 425298.

The product of its digits is 25920, while the sum is 33.

The square root of 644161335 is about 25380.3336266488. Note that the first 3 decimals coincide. The cubic root of 644161335 is about 863.6376183596.

It can be divided in two parts, 6441 and 61335, that added together give a palindrome (67776).

The spelling of 644161335 in words is "six hundred forty-four million, one hundred sixty-one thousand, three hundred thirty-five".