66521047 has 2 divisors, whose sum is σ = 66521048. Its totient is φ = 66521046.

The previous prime is 66521029. The next prime is 66521069. The reversal of 66521047 is 74012566.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66521047 - 2¹⁹ = 65996759 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66521347) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33260523 + 33260524.

It is an arithmetic number, because the mean of its divisors is an integer number (33260524).

Almost surely, 2^66521047 is an apocalyptic number.

66521047 is a deficient number, since it is larger than the sum of its proper divisors (1).

66521047 is an equidigital number, since it uses as much as digits as its factorization.

66521047 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10080, while the sum is 31.

The square root of 66521047 is about 8156.0435874264. The cubic root of 66521047 is about 405.1846884119.

It can be divided in two parts, 665 and 21047, that added together give a palindrome (21712).

The spelling of 66521047 in words is "sixty-six million, five hundred twenty-one thousand, forty-seven".