661560071 has 2 divisors, whose sum is σ = 661560072. Its totient is φ = 661560070.

The previous prime is 661560047. The next prime is 661560073. The reversal of 661560071 is 170065166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661560071 - 2⁶ = 661560007 is a prime.

Together with 661560073, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661560073) 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 as a sum of consecutive naturals, namely, 330780035 + 330780036.

It is an arithmetic number, because the mean of its divisors is an integer number (330780036).

Almost surely, 2^661560071 is an apocalyptic number.

661560071 is a deficient number, since it is larger than the sum of its proper divisors (1).

661560071 is an equidigital number, since it uses as much as digits as its factorization.

661560071 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7560, while the sum is 32.

The square root of 661560071 is about 25720.8100766675. The cubic root of 661560071 is about 871.3442341091.

The spelling of 661560071 in words is "six hundred sixty-one million, five hundred sixty thousand, seventy-one".