645981336 has 192 divisors, whose sum is σ = 2349285120. Its totient is φ = 154863360.

The previous prime is 645981319. The next prime is 645981373. The reversal of 645981336 is 633189546.

It is a junction number, because it is equal to n+sod(n) for n = 645981291 and 645981300.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 67591 + ... + 76553.

It is an arithmetic number, because the mean of its divisors is an integer number (12235860).

Almost surely, 2^645981336 is an apocalyptic number.

645981336 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645981336, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1174642560).

645981336 is an abundant number, since it is smaller than the sum of its proper divisors (1703303784).

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

645981336 is a wasteful number, since it uses less digits than its factorization.

645981336 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9006 (or 8999 counting only the distinct ones).

The product of its digits is 466560, while the sum is 45.

The square root of 645981336 is about 25416.1628889964. The cubic root of 645981336 is about 864.4502218860.

The spelling of 645981336 in words is "six hundred forty-five million, nine hundred eighty-one thousand, three hundred thirty-six".