661908672 has 112 divisors (see below), whose sum is σ = 1970328800. Its totient is φ = 220589568.

The previous prime is 661908641. The next prime is 661908677. The reversal of 661908672 is 276809166.

It is not an unprimeable number, because it can be changed into a prime (661908677) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 137604 + ... + 142332.

Almost surely, 2^661908672 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 661908672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (985164400).

661908672 is an abundant number, since it is smaller than the sum of its proper divisors (1308420128).

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

661908672 is an frugal number, since it uses more digits than its factorization.

661908672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4762 (or 4734 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 45.

The square root of 661908672 is about 25727.5858175617. The cubic root of 661908672 is about 871.4972553022.

The spelling of 661908672 in words is "six hundred sixty-one million, nine hundred eight thousand, six hundred seventy-two".