644236340 has 48 divisors (see below), whose sum is σ = 1500932160. Its totient is φ = 230292480.

The previous prime is 644236337. The next prime is 644236343. The reversal of 644236340 is 43632446.

It is an interprime number because it is at equal distance from previous prime (644236337) and next prime (644236343).

It is a junction number, because it is equal to n+sod(n) for n = 644236297 and 644236306.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644236343) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11837 + ... + 37796.

It is an arithmetic number, because the mean of its divisors is an integer number (31269420).

Almost surely, 2^644236340 is an apocalyptic number.

It is an amenable number.

644236340 is an abundant number, since it is smaller than the sum of its proper divisors (856695820).

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

644236340 is a wasteful number, since it uses less digits than its factorization.

644236340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49712 (or 49710 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 32.

The square root of 644236340 is about 25381.8112040886. The cubic root of 644236340 is about 863.6711372014.

Adding to 644236340 its reverse (43632446), we get a palindrome (687868786).

The spelling of 644236340 in words is "six hundred forty-four million, two hundred thirty-six thousand, three hundred forty".