644473741 has 4 divisors (see below), whose sum is σ = 646573312. Its totient is φ = 642374172.

The previous prime is 644473721. The next prime is 644473747. The reversal of 644473741 is 147374446.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 644473741 - 2¹⁷ = 644342669 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644473694 and 644473703.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644473747) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1049325 + ... + 1049938.

It is an arithmetic number, because the mean of its divisors is an integer number (161643328).

Almost surely, 2^644473741 is an apocalyptic number.

It is an amenable number.

644473741 is a deficient number, since it is larger than the sum of its proper divisors (2099571).

644473741 is a wasteful number, since it uses less digits than its factorization.

644473741 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2099570.

The product of its digits is 225792, while the sum is 40.

The square root of 644473741 is about 25386.4873702527. The cubic root of 644473741 is about 863.7772117369. Note that the first 3 decimals are identical.

The spelling of 644473741 in words is "six hundred forty-four million, four hundred seventy-three thousand, seven hundred forty-one".