661520544 has 48 divisors (see below), whose sum is σ = 1744132320. Its totient is φ = 219536640.

The previous prime is 661520533. The next prime is 661520551. The reversal of 661520544 is 445025166.

It is a tau number, because it is divible by the number of its divisors (48).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6939 + ... + 37029.

It is an arithmetic number, because the mean of its divisors is an integer number (36336090).

Almost surely, 2^661520544 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 661520544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (872066160).

661520544 is an abundant number, since it is smaller than the sum of its proper divisors (1082611776).

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

661520544 is a wasteful number, since it uses less digits than its factorization.

661520544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30333 (or 30325 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 33.

The square root of 661520544 is about 25720.0416795930. The cubic root of 661520544 is about 871.3268800239.

The spelling of 661520544 in words is "six hundred sixty-one million, five hundred twenty thousand, five hundred forty-four".