644122381642 has 8 divisors (see below), whose sum is σ = 966393763236. Its totient is φ = 321991127232.

The previous prime is 644122381621. The next prime is 644122381667. The reversal of 644122381642 is 246183221446.

It can be written as a sum of positive squares in 2 ways, for example, as 517278846841 + 126843534801 = 719221^2 + 356151^2 .

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

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, 35020303 + ... + 35038690.

Almost surely, 2^644122381642 is an apocalyptic number.

644122381642 is a deficient number, since it is larger than the sum of its proper divisors (322271381594).

644122381642 is a wasteful number, since it uses less digits than its factorization.

644122381642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70063592.

The product of its digits is 442368, while the sum is 43.

The spelling of 644122381642 in words is "six hundred forty-four billion, one hundred twenty-two million, three hundred eighty-one thousand, six hundred forty-two".