661045507872 has 96 divisors (see below), whose sum is σ = 1743367691520. Its totient is φ = 219317729280.

The previous prime is 661045507831. The next prime is 661045507939. The reversal of 661045507872 is 278705540166.

661045507872 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (96).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 87656422 + ... + 87663962.

It is an arithmetic number, because the mean of its divisors is an integer number (18160080120).

Almost surely, 2^661045507872 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 661045507872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (871683845760).

661045507872 is an abundant number, since it is smaller than the sum of its proper divisors (1082322183648).

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

661045507872 is a wasteful number, since it uses less digits than its factorization.

661045507872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11706 (or 11698 counting only the distinct ones).

The product of its (nonzero) digits is 2822400, while the sum is 51.

The spelling of 661045507872 in words is "six hundred sixty-one billion, forty-five million, five hundred seven thousand, eight hundred seventy-two".