644219145 has 24 divisors (see below), whose sum is σ = 1117865736. Its totient is φ = 343208448.

The previous prime is 644219143. The next prime is 644219159. The reversal of 644219145 is 541912446.

644219145 is a `hidden beast` number, since 644 + 2 + 1 + 9 + 1 + 4 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 301821129 + 342398016 = 17373^2 + 18504^2 .

It is not a de Polignac number, because 644219145 - 2¹ = 644219143 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644219141) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 36639 + ... + 51291.

It is an arithmetic number, because the mean of its divisors is an integer number (46577739).

Almost surely, 2^644219145 is an apocalyptic number.

It is an amenable number.

644219145 is a deficient number, since it is larger than the sum of its proper divisors (473646591).

644219145 is a wasteful number, since it uses less digits than its factorization.

644219145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15641 (or 15638 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 644219145 is about 25381.4724750161. The cubic root of 644219145 is about 863.6634531904.

The spelling of 644219145 in words is "six hundred forty-four million, two hundred nineteen thousand, one hundred forty-five".