661100550 has 96 divisors (see below), whose sum is σ = 1806741504. Its totient is φ = 158640000.

The previous prime is 661100549. The next prime is 661100581. The reversal of 661100550 is 55001166.

It is a self number, because there is not a number n which added to its sum of digits gives 661100550.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 164667 + ... + 168633.

It is an arithmetic number, because the mean of its divisors is an integer number (18820224).

Almost surely, 2^661100550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661100550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (903370752).

661100550 is an abundant number, since it is smaller than the sum of its proper divisors (1145640954).

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

661100550 is a wasteful number, since it uses less digits than its factorization.

661100550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4094 (or 4089 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 24.

The square root of 661100550 is about 25711.8756608692. The cubic root of 661100550 is about 871.1424415415.

The spelling of 661100550 in words is "six hundred sixty-one million, one hundred thousand, five hundred fifty".