66500940421 has 2 divisors, whose sum is σ = 66500940422. Its totient is φ = 66500940420.

The previous prime is 66500940347. The next prime is 66500940449. The reversal of 66500940421 is 12404900566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64369271521 + 2131668900 = 253711^2 + 46170^2 .

It is a cyclic number.

It is not a de Polignac number, because 66500940421 - 2⁷ = 66500940293 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66500940721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33250470210 + 33250470211.

It is an arithmetic number, because the mean of its divisors is an integer number (33250470211).

Almost surely, 2^66500940421 is an apocalyptic number.

It is an amenable number.

66500940421 is a deficient number, since it is larger than the sum of its proper divisors (1).

66500940421 is an equidigital number, since it uses as much as digits as its factorization.

66500940421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 51840, while the sum is 37.

The spelling of 66500940421 in words is "sixty-six billion, five hundred million, nine hundred forty thousand, four hundred twenty-one".