661111550 has 96 divisors (see below), whose sum is σ = 1401472800. Its totient is φ = 229824000.

The previous prime is 661111519. The next prime is 661111553. The reversal of 661111550 is 55111166.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661111553) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2886836 + ... + 2887064.

It is an arithmetic number, because the mean of its divisors is an integer number (14598675).

Almost surely, 2^661111550 is an apocalyptic number.

661111550 is an abundant number, since it is smaller than the sum of its proper divisors (740361250).

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

661111550 is a wasteful number, since it uses less digits than its factorization.

661111550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 462 (or 457 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 26.

The square root of 661111550 is about 25712.0895689168. The cubic root of 661111550 is about 871.1472731382.

It can be divided in two parts, 661 and 111550, that added together give a palindrome (112211).

The spelling of 661111550 in words is "six hundred sixty-one million, one hundred eleven thousand, five hundred fifty".