66553961 has 2 divisors, whose sum is σ = 66553962. Its totient is φ = 66553960.

The previous prime is 66553943. The next prime is 66553999. The reversal of 66553961 is 16935566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 52113961 + 14440000 = 7219^2 + 3800^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66553961 is a prime.

It is not a weakly prime, because it can be changed into another prime (66553901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33276980 + 33276981.

It is an arithmetic number, because the mean of its divisors is an integer number (33276981).

Almost surely, 2^66553961 is an apocalyptic number.

It is an amenable number.

66553961 is a deficient number, since it is larger than the sum of its proper divisors (1).

66553961 is an equidigital number, since it uses as much as digits as its factorization.

66553961 is an odious number, because the sum of its binary digits is odd.

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

The square root of 66553961 is about 8158.0611054343. The cubic root of 66553961 is about 405.2515046076.

The spelling of 66553961 in words is "sixty-six million, five hundred fifty-three thousand, nine hundred sixty-one".