661611655642 has 8 divisors (see below), whose sum is σ = 1134191409696. Its totient is φ = 283547852412.

The previous prime is 661611655637. The next prime is 661611655643. The reversal of 661611655642 is 246556116166.

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

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 3 ways as a sum of consecutive naturals, for example, 23628987688 + ... + 23628987715.

It is an arithmetic number, because the mean of its divisors is an integer number (141773926212).

Almost surely, 2^661611655642 is an apocalyptic number.

661611655642 is a deficient number, since it is larger than the sum of its proper divisors (472579754054).

661611655642 is a wasteful number, since it uses less digits than its factorization.

661611655642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47257975412.

The product of its digits is 1555200, while the sum is 49.

The spelling of 661611655642 in words is "six hundred sixty-one billion, six hundred eleven million, six hundred fifty-five thousand, six hundred forty-two".