661555512 has 80 divisors (see below), whose sum is σ = 1873951200. Its totient is φ = 218021760.

The previous prime is 661555501. The next prime is 661555513. The reversal of 661555512 is 215555166.

661555512 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661555513) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 51937 + ... + 63407.

It is an arithmetic number, because the mean of its divisors is an integer number (23424390).

Almost surely, 2^661555512 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 661555512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (936975600).

661555512 is an abundant number, since it is smaller than the sum of its proper divisors (1212395688).

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

661555512 is a wasteful number, since it uses less digits than its factorization.

661555512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11578 (or 11565 counting only the distinct ones).

The product of its digits is 45000, while the sum is 36.

The square root of 661555512 is about 25720.7214517789. The cubic root of 661555512 is about 871.3422325436.

The spelling of 661555512 in words is "six hundred sixty-one million, five hundred fifty-five thousand, five hundred twelve".