661273057 has 2 divisors, whose sum is σ = 661273058. Its totient is φ = 661273056.

The previous prime is 661273043. The next prime is 661273061. The reversal of 661273057 is 750372166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 483824016 + 177449041 = 21996^2 + 13321^2 .

It is a cyclic number.

It is not a de Polignac number, because 661273057 - 2⁷ = 661272929 is a prime.

It is not a weakly prime, because it can be changed into another prime (661273007) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330636528 + 330636529.

It is an arithmetic number, because the mean of its divisors is an integer number (330636529).

Almost surely, 2^661273057 is an apocalyptic number.

It is an amenable number.

661273057 is a deficient number, since it is larger than the sum of its proper divisors (1).

661273057 is an equidigital number, since it uses as much as digits as its factorization.

661273057 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 52920, while the sum is 37.

The square root of 661273057 is about 25715.2300592470. The cubic root of 661273057 is about 871.2182066677.

The spelling of 661273057 in words is "six hundred sixty-one million, two hundred seventy-three thousand, fifty-seven".