661668848360644 has 6 divisors (see below), whose sum is σ = 1157920484631134. Its totient is φ = 330834424180320.

The previous prime is 661668848360627. The next prime is 661668848360677. The reversal of 661668848360644 is 446063848866166.

It can be written as a sum of positive squares in only one way, i.e., 430753836252100 + 230915012108544 = 20754610^2 + 15195888^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82708606045077 + ... + 82708606045084.

Almost surely, 2^{661668848360644} is an apocalyptic number.

It is an amenable number.

661668848360644 is a deficient number, since it is larger than the sum of its proper divisors (496251636270490).

661668848360644 is a wasteful number, since it uses less digits than its factorization.

661668848360644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165417212090165 (or 165417212090163 counting only the distinct ones).

The product of its (nonzero) digits is 4586471424, while the sum is 76.

The spelling of 661668848360644 in words is "six hundred sixty-one trillion, six hundred sixty-eight billion, eight hundred forty-eight million, three hundred sixty thousand, six hundred forty-four".