661750213 has 2 divisors, whose sum is σ = 661750214. Its totient is φ = 661750212.

The previous prime is 661750189. The next prime is 661750237. The reversal of 661750213 is 312057166.

It is a balanced prime because it is at equal distance from previous prime (661750189) and next prime (661750237).

It can be written as a sum of positive squares in only one way, i.e., 404532769 + 257217444 = 20113^2 + 16038^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661750213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661750253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330875106 + 330875107.

It is an arithmetic number, because the mean of its divisors is an integer number (330875107).

Almost surely, 2^661750213 is an apocalyptic number.

It is an amenable number.

661750213 is a deficient number, since it is larger than the sum of its proper divisors (1).

661750213 is an equidigital number, since it uses as much as digits as its factorization.

661750213 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 661750213 is about 25724.5060788346. The cubic root of 661750213 is about 871.4277051206.

The spelling of 661750213 in words is "six hundred sixty-one million, seven hundred fifty thousand, two hundred thirteen".