645869406 has 128 divisors (see below), whose sum is σ = 1698278400. Its totient is φ = 158902272.

The previous prime is 645869387. The next prime is 645869437. The reversal of 645869406 is 604968546.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1382785 + ... + 1383251.

It is an arithmetic number, because the mean of its divisors is an integer number (13267800).

Almost surely, 2^645869406 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645869406, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (849139200).

645869406 is an abundant number, since it is smaller than the sum of its proper divisors (1052408994).

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

645869406 is a wasteful number, since it uses less digits than its factorization.

645869406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 658.

The product of its (nonzero) digits is 1244160, while the sum is 48.

The square root of 645869406 is about 25413.9608483211. The cubic root of 645869406 is about 864.4002908756.

The spelling of 645869406 in words is "six hundred forty-five million, eight hundred sixty-nine thousand, four hundred six".