661525543 has 4 divisors (see below), whose sum is σ = 756029200. Its totient is φ = 567021888.

The previous prime is 661525537. The next prime is 661525561. The reversal of 661525543 is 345525166.

661525543 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 661525543 - 2⁵ = 661525511 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661525043) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47251818 + ... + 47251831.

It is an arithmetic number, because the mean of its divisors is an integer number (189007300).

Almost surely, 2^661525543 is an apocalyptic number.

661525543 is a deficient number, since it is larger than the sum of its proper divisors (94503657).

661525543 is an equidigital number, since it uses as much as digits as its factorization.

661525543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94503656.

The product of its digits is 108000, while the sum is 37.

The square root of 661525543 is about 25720.1388604339. The cubic root of 661525543 is about 871.3290748421.

The spelling of 661525543 in words is "six hundred sixty-one million, five hundred twenty-five thousand, five hundred forty-three".