644553545355446 has 16 divisors (see below), whose sum is σ = 976406880448368. Its totient is φ = 319084611252000.

The previous prime is 644553545355443. The next prime is 644553545355449.

It is a happy number.

644553545355446 is nontrivially palindromic in base 10.

It is an interprime number because it is at equal distance from previous prime (644553545355443) and next prime (644553545355449).

It is a super-3 number, since 3×644553545355446³ (a number of 45 digits) contains 333 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644553545355443) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44075276 + ... + 56848368.

It is an arithmetic number, because the mean of its divisors is an integer number (61025430028023).

Almost surely, 2^{644553545355446} is an apocalyptic number.

644553545355446 is a deficient number, since it is larger than the sum of its proper divisors (331853335092922).

644553545355446 is a wasteful number, since it uses less digits than its factorization.

644553545355446 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13023007.

The product of its digits is 5184000000, while the sum is 68.

The spelling of 644553545355446 in words is "six hundred forty-four trillion, five hundred fifty-three billion, five hundred forty-five million, three hundred fifty-five thousand, four hundred forty-six".