661606220 has 72 divisors (see below), whose sum is σ = 1607650800. Its totient is φ = 227905920.

The previous prime is 661606193. The next prime is 661606249. The reversal of 661606220 is 22606166.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 38786 + ... + 53174.

Almost surely, 2^661606220 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 661606220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (803825400).

661606220 is an abundant number, since it is smaller than the sum of its proper divisors (946044580).

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

661606220 is a wasteful number, since it uses less digits than its factorization.

661606220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14439 (or 14426 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 661606220 is about 25721.7071750691. The cubic root of 661606220 is about 871.3644946678.

The spelling of 661606220 in words is "six hundred sixty-one million, six hundred six thousand, two hundred twenty".