646979796 has 54 divisors (see below), whose sum is σ = 1689968826. Its totient is φ = 208692000.

The previous prime is 646979779. The next prime is 646979797. The reversal of 646979796 is 697979646.

It can be written as a sum of positive squares in only one way, i.e., 457532100 + 189447696 = 21390^2 + 13764^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646979797) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 25246 + ... + 43946.

It is an arithmetic number, because the mean of its divisors is an integer number (31295719).

Almost surely, 2^646979796 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 646979796, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (844984413).

646979796 is an abundant number, since it is smaller than the sum of its proper divisors (1042989030).

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

646979796 is a wasteful number, since it uses less digits than its factorization.

646979796 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18773 (or 18737 counting only the distinct ones).

The product of its digits is 30862944, while the sum is 63.

The square root of 646979796 is about 25435.7975302525. The cubic root of 646979796 is about 864.8953713091.

The spelling of 646979796 in words is "six hundred forty-six million, nine hundred seventy-nine thousand, seven hundred ninety-six".