644345401 has 8 divisors (see below), whose sum is σ = 736566464. Its totient is φ = 552167280.

The previous prime is 644345399. The next prime is 644345477. The reversal of 644345401 is 104543446.

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

It is not a de Polignac number, because 644345401 - 2¹ = 644345399 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644349401) 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, 33691 + ... + 49231.

It is an arithmetic number, because the mean of its divisors is an integer number (92070808).

Almost surely, 2^644345401 is an apocalyptic number.

It is an amenable number.

644345401 is a deficient number, since it is larger than the sum of its proper divisors (92221063).

644345401 is a wasteful number, since it uses less digits than its factorization.

644345401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21471.

The product of its (nonzero) digits is 23040, while the sum is 31.

The square root of 644345401 is about 25383.9595217137. The cubic root of 644345401 is about 863.7198706228.

Adding to 644345401 its reverse (104543446), we get a palindrome (748888847).

The spelling of 644345401 in words is "six hundred forty-four million, three hundred forty-five thousand, four hundred one".