644074161 has 4 divisors (see below), whose sum is σ = 858765552. Its totient is φ = 429382772.

The previous prime is 644074159. The next prime is 644074163. The reversal of 644074161 is 161470446.

644074161 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 an interprime number because it is at equal distance from previous prime (644074159) and next prime (644074163).

It is a cyclic number.

It is not a de Polignac number, because 644074161 - 2¹ = 644074159 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644074163) 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, 107345691 + ... + 107345696.

It is an arithmetic number, because the mean of its divisors is an integer number (214691388).

Almost surely, 2^644074161 is an apocalyptic number.

It is an amenable number.

644074161 is a deficient number, since it is larger than the sum of its proper divisors (214691391).

644074161 is a wasteful number, since it uses less digits than its factorization.

644074161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214691390.

The product of its (nonzero) digits is 16128, while the sum is 33.

The square root of 644074161 is about 25378.6162152313. The cubic root of 644074161 is about 863.5986580671.

It can be divided in two parts, 6440 and 74161, that added together give a triangular number (80601 = T₄₀₁).

The spelling of 644074161 in words is "six hundred forty-four million, seventy-four thousand, one hundred sixty-one".