661813984 has 48 divisors (see below), whose sum is σ = 1410614352. Its totient is φ = 303833088.

The previous prime is 661813963. The next prime is 661814039. The reversal of 661813984 is 489318166.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76167 + ... + 84409.

It is an arithmetic number, because the mean of its divisors is an integer number (29387799).

Almost surely, 2^661813984 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 661813984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (705307176).

661813984 is an abundant number, since it is smaller than the sum of its proper divisors (748800368).

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

661813984 is a wasteful number, since it uses less digits than its factorization.

661813984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8459 (or 8451 counting only the distinct ones).

The product of its digits is 248832, while the sum is 46.

The square root of 661813984 is about 25725.7455479914. The cubic root of 661813984 is about 871.4556965642.

It can be divided in two parts, 6618 and 13984, that added together give a palindrome (20602).

The spelling of 661813984 in words is "six hundred sixty-one million, eight hundred thirteen thousand, nine hundred eighty-four".