661684224 has 128 divisors (see below), whose sum is σ = 1811911680. Its totient is φ = 214695936.

The previous prime is 661684211. The next prime is 661684241. The reversal of 661684224 is 422486166.

It is a tau number, because it is divible by the number of its divisors (128).

It is a nude number because it is divisible by every one of its digits.

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, 5210049 + ... + 5210175.

It is an arithmetic number, because the mean of its divisors is an integer number (14155560).

Almost surely, 2^661684224 is an apocalyptic number.

661684224 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661684224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (905955840).

661684224 is an abundant number, since it is smaller than the sum of its proper divisors (1150227456).

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

661684224 is an equidigital number, since it uses as much as digits as its factorization.

661684224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213 (or 185 counting only the distinct ones).

The product of its digits is 110592, while the sum is 39.

The square root of 661684224 is about 25723.2234371978. The cubic root of 661684224 is about 871.3987382218.

The spelling of 661684224 in words is "six hundred sixty-one million, six hundred eighty-four thousand, two hundred twenty-four".