661366671 has 24 divisors (see below), whose sum is σ = 1026984960. Its totient is φ = 377484912.

The previous prime is 661366669. The next prime is 661366681. The reversal of 661366671 is 176663166.

It is not a de Polignac number, because 661366671 - 2¹ = 661366669 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661366681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 157720 + ... + 161858.

It is an arithmetic number, because the mean of its divisors is an integer number (42791040).

Almost surely, 2^661366671 is an apocalyptic number.

661366671 is a deficient number, since it is larger than the sum of its proper divisors (365618289).

661366671 is a wasteful number, since it uses less digits than its factorization.

661366671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5243 (or 5236 counting only the distinct ones).

The product of its digits is 163296, while the sum is 42.

The square root of 661366671 is about 25717.0502002076. The cubic root of 661366671 is about 871.2593164493.

The spelling of 661366671 in words is "six hundred sixty-one million, three hundred sixty-six thousand, six hundred seventy-one".