661605254601 has 16 divisors (see below), whose sum is σ = 934047785664. Its totient is φ = 415117382144.

The previous prime is 661605254599. The next prime is 661605254677. The reversal of 661605254601 is 106452506166.

It is a cyclic number.

It is not a de Polignac number, because 661605254601 - 2¹ = 661605254599 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661605253601) 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 15 ways as a sum of consecutive naturals, for example, 4542430 + ... + 4685816.

It is an arithmetic number, because the mean of its divisors is an integer number (58377986604).

Almost surely, 2^661605254601 is an apocalyptic number.

It is an amenable number.

661605254601 is a deficient number, since it is larger than the sum of its proper divisors (272442531063).

661605254601 is a wasteful number, since it uses less digits than its factorization.

661605254601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 233880.

The product of its (nonzero) digits is 259200, while the sum is 42.

The spelling of 661605254601 in words is "six hundred sixty-one billion, six hundred five million, two hundred fifty-four thousand, six hundred one".