661015680 has 256 divisors, whose sum is σ = 2307191040. Its totient is φ = 159989760.

The previous prime is 661015679. The next prime is 661015717. The reversal of 661015680 is 86510166.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1771974 + ... + 1772346.

It is an arithmetic number, because the mean of its divisors is an integer number (9012465).

Almost surely, 2^661015680 is an apocalyptic number.

661015680 is a gapful number since it is divisible by the number (60) 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 661015680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1153595520).

661015680 is an abundant number, since it is smaller than the sum of its proper divisors (1646175360).

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

661015680 is a wasteful number, since it uses less digits than its factorization.

661015680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 479 (or 467 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 661015680 is about 25710.2252032144. The cubic root of 661015680 is about 871.1051617747.

The spelling of 661015680 in words is "six hundred sixty-one million, fifteen thousand, six hundred eighty".