66621559 has 2 divisors, whose sum is σ = 66621560. Its totient is φ = 66621558.

The previous prime is 66621557. The next prime is 66621587. The reversal of 66621559 is 95512666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66621559 - 2¹ = 66621557 is a prime.

Together with 66621557, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66621551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33310779 + 33310780.

It is an arithmetic number, because the mean of its divisors is an integer number (33310780).

Almost surely, 2^66621559 is an apocalyptic number.

66621559 is a deficient number, since it is larger than the sum of its proper divisors (1).

66621559 is an equidigital number, since it uses as much as digits as its factorization.

66621559 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 97200, while the sum is 40.

The square root of 66621559 is about 8162.2030727004. The cubic root of 66621559 is about 405.3886610913.

The spelling of 66621559 in words is "sixty-six million, six hundred twenty-one thousand, five hundred fifty-nine".