647651816 has 48 divisors (see below), whose sum is σ = 1425206340. Its totient is φ = 275089920.

The previous prime is 647651801. The next prime is 647651821. The reversal of 647651816 is 618156746.

It can be written as a sum of positive squares in 2 ways, for example, as 370562500 + 277089316 = 19250^2 + 16646^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 36986 + ... + 51606.

Almost surely, 2^647651816 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 647651816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (712603170).

647651816 is an abundant number, since it is smaller than the sum of its proper divisors (777554524).

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

647651816 is a wasteful number, since it uses less digits than its factorization.

647651816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14754 (or 14743 counting only the distinct ones).

The product of its digits is 241920, while the sum is 44.

The square root of 647651816 is about 25449.0042241342. The cubic root of 647651816 is about 865.1947242236.

The spelling of 647651816 in words is "six hundred forty-seven million, six hundred fifty-one thousand, eight hundred sixteen".