661611655641 has 8 divisors (see below), whose sum is σ = 882196175680. Its totient is φ = 441050786352.

The previous prime is 661611655637. The next prime is 661611655643. The reversal of 661611655641 is 146556116166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 661611655641 - 2² = 661611655637 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (661611655643) 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 7 ways as a sum of consecutive naturals, for example, 5847310 + ... + 5959383.

It is an arithmetic number, because the mean of its divisors is an integer number (110274521960).

Almost surely, 2^661611655641 is an apocalyptic number.

It is an amenable number.

661611655641 is a deficient number, since it is larger than the sum of its proper divisors (220584520039).

661611655641 is a wasteful number, since it uses less digits than its factorization.

661611655641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11825375.

The product of its digits is 777600, while the sum is 48.

The spelling of 661611655641 in words is "six hundred sixty-one billion, six hundred eleven million, six hundred fifty-five thousand, six hundred forty-one".