645013840 has 80 divisors (see below), whose sum is σ = 1570578048. Its totient is φ = 245887488.

The previous prime is 645013829. The next prime is 645013841. The reversal of 645013840 is 48310546.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645013841) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 730039 + ... + 730921.

Almost surely, 2^645013840 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645013840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (785289024).

645013840 is an abundant number, since it is smaller than the sum of its proper divisors (925564208).

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

645013840 is a wasteful number, since it uses less digits than its factorization.

645013840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1316 (or 1310 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 31.

The square root of 645013840 is about 25397.1226716729. The cubic root of 645013840 is about 864.0184395356.

The spelling of 645013840 in words is "six hundred forty-five million, thirteen thousand, eight hundred forty".