644551643242 has 8 divisors (see below), whose sum is σ = 1041198808356. Its totient is φ = 297485373792.

The previous prime is 644551643213. The next prime is 644551643269. The reversal of 644551643242 is 242346155446.

It can be written as a sum of positive squares in 2 ways, for example, as 631610078121 + 12941565121 = 794739^2 + 113761^2 .

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

It is a super-3 number, since 3×644551643242³ (a number of 36 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 644551643192 and 644551643201.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12395223883 + ... + 12395223934.

Almost surely, 2^644551643242 is an apocalyptic number.

644551643242 is a deficient number, since it is larger than the sum of its proper divisors (396647165114).

644551643242 is a wasteful number, since it uses less digits than its factorization.

644551643242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24790447832.

The product of its digits is 2764800, while the sum is 46.

Adding to 644551643242 its reverse (242346155446), we get a palindrome (886897798688).

The spelling of 644551643242 in words is "six hundred forty-four billion, five hundred fifty-one million, six hundred forty-three thousand, two hundred forty-two".