66456521 has 2 divisors, whose sum is σ = 66456522. Its totient is φ = 66456520.

The previous prime is 66456491. The next prime is 66456581. The reversal of 66456521 is 12565466.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66015625 + 440896 = 8125^2 + 664^2 .

It is a cyclic number.

It is not a de Polignac number, because 66456521 - 2¹⁴ = 66440137 is a prime.

It is not a weakly prime, because it can be changed into another prime (66456581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33228260 + 33228261.

It is an arithmetic number, because the mean of its divisors is an integer number (33228261).

Almost surely, 2^66456521 is an apocalyptic number.

It is an amenable number.

66456521 is a deficient number, since it is larger than the sum of its proper divisors (1).

66456521 is an equidigital number, since it uses as much as digits as its factorization.

66456521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 43200, while the sum is 35.

The square root of 66456521 is about 8152.0869107241. The cubic root of 66456521 is about 405.0536351260.

The spelling of 66456521 in words is "sixty-six million, four hundred fifty-six thousand, five hundred twenty-one".