661558752 has 216 divisors, whose sum is σ = 2053383696. Its totient is φ = 209392128.

The previous prime is 661558691. The next prime is 661558753. The reversal of 661558752 is 257855166.

661558752 is a `hidden beast` number, since 6 + 6 + 15 + 587 + 52 = 666.

It is a tau number, because it is divible by the number of its divisors (216).

It is a junction number, because it is equal to n+sod(n) for n = 661558698 and 661558707.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661558753) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 4828828 + ... + 4828964.

It is an arithmetic number, because the mean of its divisors is an integer number (9506406).

Almost surely, 2^661558752 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 661558752, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1026691848).

661558752 is an abundant number, since it is smaller than the sum of its proper divisors (1391824944).

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

661558752 is an equidigital number, since it uses as much as digits as its factorization.

661558752 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194 (or 165 counting only the distinct ones).

The product of its digits is 504000, while the sum is 45.

The square root of 661558752 is about 25720.7844359382. The cubic root of 661558752 is about 871.3436550214.

The spelling of 661558752 in words is "six hundred sixty-one million, five hundred fifty-eight thousand, seven hundred fifty-two".