661666501158 has 64 divisors (see below), whose sum is σ = 1487431959552. Its totient is φ = 194693178240.

The previous prime is 661666501151. The next prime is 661666501159. The reversal of 661666501158 is 851105666166.

It is a self number, because there is not a number n which added to its sum of digits gives 661666501158.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661666501151) 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 31 ways as a sum of consecutive naturals, for example, 8206903 + ... + 8287133.

It is an arithmetic number, because the mean of its divisors is an integer number (23241124368).

Almost surely, 2^661666501158 is an apocalyptic number.

661666501158 is an abundant number, since it is smaller than the sum of its proper divisors (825765458394).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661666501158 is a wasteful number, since it uses less digits than its factorization.

661666501158 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84869.

The product of its (nonzero) digits is 1555200, while the sum is 51.

The spelling of 661666501158 in words is "six hundred sixty-one billion, six hundred sixty-six million, five hundred one thousand, one hundred fifty-eight".