661125541 has 4 divisors (see below), whose sum is σ = 661307500. Its totient is φ = 660943584.

The previous prime is 661125523. The next prime is 661125601. The reversal of 661125541 is 145521166.

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

It can be written as a sum of positive squares in 2 ways, for example, as 439740900 + 221384641 = 20970^2 + 14879^2 .

It is a cyclic number.

It is not a de Polignac number, because 661125541 - 2²⁹ = 124254629 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 (661125511) 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 3 ways as a sum of consecutive naturals, for example, 85416 + ... + 92833.

It is an arithmetic number, because the mean of its divisors is an integer number (165326875).

Almost surely, 2^661125541 is an apocalyptic number.

It is an amenable number.

661125541 is a deficient number, since it is larger than the sum of its proper divisors (181959).

661125541 is a wasteful number, since it uses less digits than its factorization.

661125541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 181958.

The product of its digits is 7200, while the sum is 31.

The square root of 661125541 is about 25712.3616379359. The cubic root of 661125541 is about 871.1534184125.

The spelling of 661125541 in words is "six hundred sixty-one million, one hundred twenty-five thousand, five hundred forty-one".