665686240551 has 24 divisors (see below), whose sum is σ = 987885609984. Its totient is φ = 431747534160.

The previous prime is 665686240543. The next prime is 665686240561. The reversal of 665686240551 is 155042686566.

665686240551 is a `hidden beast` number, since 6 + 6 + 5 + 6 + 8 + 624 + 0 + 5 + 5 + 1 = 666.

It is not a de Polignac number, because 665686240551 - 2³ = 665686240543 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665686240561) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4641115 + ... + 4782396.

It is an arithmetic number, because the mean of its divisors is an integer number (41161900416).

Almost surely, 2^665686240551 is an apocalyptic number.

665686240551 is a deficient number, since it is larger than the sum of its proper divisors (322199369433).

665686240551 is a wasteful number, since it uses less digits than its factorization.

665686240551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9423731 (or 9423728 counting only the distinct ones).

The product of its (nonzero) digits is 10368000, while the sum is 54.

The spelling of 665686240551 in words is "six hundred sixty-five billion, six hundred eighty-six million, two hundred forty thousand, five hundred fifty-one".