645983910 has 288 divisors, whose sum is σ = 2073970080. Its totient is φ = 144555840.

The previous prime is 645983909. The next prime is 645983927. The reversal of 645983910 is 19389546.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 49691064 + ... + 49691076.

It is an arithmetic number, because the mean of its divisors is an integer number (7201285).

Almost surely, 2^645983910 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645983910, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1036985040).

645983910 is an abundant number, since it is smaller than the sum of its proper divisors (1427986170).

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

645983910 is a wasteful number, since it uses less digits than its factorization.

645983910 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83 (or 34 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 45.

The square root of 645983910 is about 25416.2135260152. The cubic root of 645983910 is about 864.4513700574.

The spelling of 645983910 in words is "six hundred forty-five million, nine hundred eighty-three thousand, nine hundred ten".