644630293 has 8 divisors (see below), whose sum is σ = 690220440. Its totient is φ = 599892480.

The previous prime is 644630279. The next prime is 644630297. The reversal of 644630293 is 392036446.

It can be written as a sum of positive squares in 4 ways, for example, as 13264164 + 631366129 = 3642^2 + 25127^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 644630293 - 2⁹ = 644629781 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644630297) 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, 211518 + ... + 214543.

It is an arithmetic number, because the mean of its divisors is an integer number (86277555).

Almost surely, 2^644630293 is an apocalyptic number.

It is an amenable number.

644630293 is a deficient number, since it is larger than the sum of its proper divisors (45590147).

644630293 is a wasteful number, since it uses less digits than its factorization.

644630293 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 426167.

The product of its (nonzero) digits is 93312, while the sum is 37.

The square root of 644630293 is about 25389.5705556435. The cubic root of 644630293 is about 863.8471474035.

The spelling of 644630293 in words is "six hundred forty-four million, six hundred thirty thousand, two hundred ninety-three".