66720553 has 2 divisors, whose sum is σ = 66720554. Its totient is φ = 66720552.

The previous prime is 66720491. The next prime is 66720559. The reversal of 66720553 is 35502766.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 56145049 + 10575504 = 7493^2 + 3252^2 .

It is a cyclic number.

It is not a de Polignac number, because 66720553 - 2⁹ = 66720041 is a prime.

It is not a weakly prime, because it can be changed into another prime (66720559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33360276 + 33360277.

It is an arithmetic number, because the mean of its divisors is an integer number (33360277).

Almost surely, 2^66720553 is an apocalyptic number.

It is an amenable number.

66720553 is a deficient number, since it is larger than the sum of its proper divisors (1).

66720553 is an equidigital number, since it uses as much as digits as its factorization.

66720553 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 37800, while the sum is 34.

The square root of 66720553 is about 8168.2649932529. The cubic root of 66720553 is about 405.5893528043.

The spelling of 66720553 in words is "sixty-six million, seven hundred twenty thousand, five hundred fifty-three".