661180840 has 32 divisors (see below), whose sum is σ = 1489726080. Its totient is φ = 264104512.

The previous prime is 661180837. The next prime is 661180841. The reversal of 661180840 is 48081166.

It is a junction number, because it is equal to n+sod(n) for n = 661180796 and 661180805.

It is not an unprimeable number, because it can be changed into a prime (661180841) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18597 + ... + 40843.

It is an arithmetic number, because the mean of its divisors is an integer number (46553940).

Almost surely, 2^661180840 is an apocalyptic number.

It is an amenable number.

661180840 is an abundant number, since it is smaller than the sum of its proper divisors (828545240).

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

661180840 is a wasteful number, since it uses less digits than its factorization.

661180840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23001 (or 22997 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 34.

The square root of 661180840 is about 25713.4369542463. The cubic root of 661180840 is about 871.1777065730.

The spelling of 661180840 in words is "six hundred sixty-one million, one hundred eighty thousand, eight hundred forty".