661656271 has 4 divisors (see below), whose sum is σ = 675734112. Its totient is φ = 647578432.

The previous prime is 661656239. The next prime is 661656299. The reversal of 661656271 is 172656166.

661656271 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 661656271 - 2⁵ = 661656239 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661656211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7038850 + ... + 7038943.

It is an arithmetic number, because the mean of its divisors is an integer number (168933528).

Almost surely, 2^661656271 is an apocalyptic number.

661656271 is a deficient number, since it is larger than the sum of its proper divisors (14077841).

661656271 is a wasteful number, since it uses less digits than its factorization.

661656271 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14077840.

The product of its digits is 90720, while the sum is 40.

The square root of 661656271 is about 25722.6800897574. The cubic root of 661656271 is about 871.3864672366.

The spelling of 661656271 in words is "six hundred sixty-one million, six hundred fifty-six thousand, two hundred seventy-one".