61660601655521 has 16 divisors (see below), whose sum is σ = 67784219635968. Its totient is φ = 55623393555600.

The previous prime is 61660601655511. The next prime is 61660601655529. The reversal of 61660601655521 is 12555610606616.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 61660601655521 - 2¹⁴ = 61660601639137 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 61660601655521.

It is not an unprimeable number, because it can be changed into a prime (61660601655529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19762670 + ... + 22669016.

It is an arithmetic number, because the mean of its divisors is an integer number (4236513727248).

Almost surely, 2^{61660601655521} is an apocalyptic number.

It is an amenable number.

61660601655521 is a deficient number, since it is larger than the sum of its proper divisors (6123617980447).

61660601655521 is a wasteful number, since it uses less digits than its factorization.

61660601655521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2921212.

The product of its (nonzero) digits is 1944000, while the sum is 50.

The spelling of 61660601655521 in words is "sixty-one trillion, six hundred sixty billion, six hundred one million, six hundred fifty-five thousand, five hundred twenty-one".