66975521 has 2 divisors, whose sum is σ = 66975522. Its totient is φ = 66975520.

The previous prime is 66975497. The next prime is 66975527. The reversal of 66975521 is 12557966.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 34939921 + 32035600 = 5911^2 + 5660^2 .

It is a cyclic number.

It is not a de Polignac number, because 66975521 - 2⁶ = 66975457 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66975527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33487760 + 33487761.

It is an arithmetic number, because the mean of its divisors is an integer number (33487761).

Almost surely, 2^66975521 is an apocalyptic number.

It is an amenable number.

66975521 is a deficient number, since it is larger than the sum of its proper divisors (1).

66975521 is an equidigital number, since it uses as much as digits as its factorization.

66975521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 113400, while the sum is 41.

The square root of 66975521 is about 8183.8573423539. The cubic root of 66975521 is about 406.1053400213.

The spelling of 66975521 in words is "sixty-six million, nine hundred seventy-five thousand, five hundred twenty-one".