661660616101 has 4 divisors (see below), whose sum is σ = 663659591104. Its totient is φ = 659661641100.

The previous prime is 661660616093. The next prime is 661660616129. The reversal of 661660616101 is 101616066166.

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 661660616101 - 2³ = 661660616093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661660616191) 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, 999487005 + ... + 999487666.

It is an arithmetic number, because the mean of its divisors is an integer number (165914897776).

Almost surely, 2^661660616101 is an apocalyptic number.

It is an amenable number.

661660616101 is a deficient number, since it is larger than the sum of its proper divisors (1998975003).

661660616101 is a wasteful number, since it uses less digits than its factorization.

661660616101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1998975002.

The product of its (nonzero) digits is 46656, while the sum is 40.

The spelling of 661660616101 in words is "six hundred sixty-one billion, six hundred sixty million, six hundred sixteen thousand, one hundred one".