661544125445641 has 4 divisors (see below), whose sum is σ = 676928872549072. Its totient is φ = 646159378342212.

The previous prime is 661544125445639. The next prime is 661544125445717. The reversal of 661544125445641 is 146544521445166.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 661544125445641 - 2¹ = 661544125445639 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661544125445611) 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, 7692373551651 + ... + 7692373551736.

It is an arithmetic number, because the mean of its divisors is an integer number (169232218137268).

Almost surely, 2^{661544125445641} is an apocalyptic number.

It is an amenable number.

661544125445641 is a deficient number, since it is larger than the sum of its proper divisors (15384747103431).

661544125445641 is a wasteful number, since it uses less digits than its factorization.

661544125445641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15384747103430.

The product of its digits is 55296000, while the sum is 58.

The spelling of 661544125445641 in words is "six hundred sixty-one trillion, five hundred forty-four billion, one hundred twenty-five million, four hundred forty-five thousand, six hundred forty-one".