661275187 has 2 divisors, whose sum is σ = 661275188. Its totient is φ = 661275186.

The previous prime is 661275169. The next prime is 661275227. The reversal of 661275187 is 781572166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661275187 - 2¹⁹ = 660750899 is a prime.

It is not a weakly prime, because it can be changed into another prime (661273187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330637593 + 330637594.

It is an arithmetic number, because the mean of its divisors is an integer number (330637594).

Almost surely, 2^661275187 is an apocalyptic number.

661275187 is a deficient number, since it is larger than the sum of its proper divisors (1).

661275187 is an equidigital number, since it uses as much as digits as its factorization.

661275187 is an evil number, because the sum of its binary digits is even.

The product of its digits is 141120, while the sum is 43.

The square root of 661275187 is about 25715.2714743594. The cubic root of 661275187 is about 871.2191420820.

The spelling of 661275187 in words is "six hundred sixty-one million, two hundred seventy-five thousand, one hundred eighty-seven".