2066556721 has 2 divisors, whose sum is σ = 2066556722. Its totient is φ = 2066556720.

The previous prime is 2066556673. The next prime is 2066556731. The reversal of 2066556721 is 1276556602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1802851600 + 263705121 = 42460^2 + 16239^2 .

It is a cyclic number.

It is not a de Polignac number, because 2066556721 - 2¹³ = 2066548529 is a prime.

It is a super-2 number, since 2×2066556721² = 8541313362220543682, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (2066556731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1033278360 + 1033278361.

It is an arithmetic number, because the mean of its divisors is an integer number (1033278361).

Almost surely, 2^2066556721 is an apocalyptic number.

It is an amenable number.

2066556721 is a deficient number, since it is larger than the sum of its proper divisors (1).

2066556721 is an equidigital number, since it uses as much as digits as its factorization.

2066556721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 151200, while the sum is 40.

The square root of 2066556721 is about 45459.3963994244. The cubic root of 2066556721 is about 1273.7448565176.

The spelling of 2066556721 in words is "two billion, sixty-six million, five hundred fifty-six thousand, seven hundred twenty-one".