66953561 has 2 divisors, whose sum is σ = 66953562. Its totient is φ = 66953560.

The previous prime is 66953507. The next prime is 66953591. The reversal of 66953561 is 16535966.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52475536 + 14478025 = 7244^2 + 3805^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66953561 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66953591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33476780 + 33476781.

It is an arithmetic number, because the mean of its divisors is an integer number (33476781).

Almost surely, 2^66953561 is an apocalyptic number.

It is an amenable number.

66953561 is a deficient number, since it is larger than the sum of its proper divisors (1).

66953561 is an equidigital number, since it uses as much as digits as its factorization.

66953561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 145800, while the sum is 41.

The square root of 66953561 is about 8182.5155667435. The cubic root of 66953561 is about 406.0609504294.

The spelling of 66953561 in words is "sixty-six million, nine hundred fifty-three thousand, five hundred sixty-one".