644613142 has 4 divisors (see below), whose sum is σ = 966919716. Its totient is φ = 322306570.

The previous prime is 644613127. The next prime is 644613199. The reversal of 644613142 is 241316446.

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

It is a super-2 number, since 2×644613142² = 831052205678224328, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 161153284 + ... + 161153287.

It is an arithmetic number, because the mean of its divisors is an integer number (241729929).

Almost surely, 2^644613142 is an apocalyptic number.

644613142 is a deficient number, since it is larger than the sum of its proper divisors (322306574).

644613142 is a wasteful number, since it uses less digits than its factorization.

644613142 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322306573.

The product of its digits is 13824, while the sum is 31.

The square root of 644613142 is about 25389.2327966010. The cubic root of 644613142 is about 863.8394861781.

Adding to 644613142 its reverse (241316446), we get a palindrome (885929588).

The spelling of 644613142 in words is "six hundred forty-four million, six hundred thirteen thousand, one hundred forty-two".