644940342 has 12 divisors (see below), whose sum is σ = 1397370780. Its totient is φ = 214980108.

The previous prime is 644940323. The next prime is 644940343. The reversal of 644940342 is 243049446.

644940342 is a `hidden beast` number, since 644 + 9 + 4 + 0 + 3 + 4 + 2 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 644940297 and 644940306.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644940343) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17914992 + ... + 17915027.

It is an arithmetic number, because the mean of its divisors is an integer number (116447565).

Almost surely, 2^644940342 is an apocalyptic number.

644940342 is an abundant number, since it is smaller than the sum of its proper divisors (752430438).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644940342 is a wasteful number, since it uses less digits than its factorization.

644940342 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35830027 (or 35830024 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 36.

The square root of 644940342 is about 25395.6756555127. The cubic root of 644940342 is about 863.9856205812.

Adding to 644940342 its reverse (243049446), we get a palindrome (887989788).

The spelling of 644940342 in words is "six hundred forty-four million, nine hundred forty thousand, three hundred forty-two".