661051663365661 has 8 divisors (see below), whose sum is σ = 698355927862880. Its totient is φ = 623998606037328.

The previous prime is 661051663365619. The next prime is 661051663365673. The reversal of 661051663365661 is 166563366150166.

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

It is a cyclic number.

It is not a de Polignac number, because 661051663365661 - 2²⁵ = 661051629811229 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661051663365661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661051663365161) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 62801786811 + ... + 62801797336.

It is an arithmetic number, because the mean of its divisors is an integer number (87294490982860).

Almost surely, 2^{661051663365661} is an apocalyptic number.

It is an amenable number.

661051663365661 is a deficient number, since it is larger than the sum of its proper divisors (37304264497219).

661051663365661 is a wasteful number, since it uses less digits than its factorization.

661051663365661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125603584443.

The product of its (nonzero) digits is 62985600, while the sum is 61.

The spelling of 661051663365661 in words is "six hundred sixty-one trillion, fifty-one billion, six hundred sixty-three million, three hundred sixty-five thousand, six hundred sixty-one".