66521716 has 6 divisors (see below), whose sum is σ = 116413010. Its totient is φ = 33260856.

The previous prime is 66521699. The next prime is 66521729. The reversal of 66521716 is 61712566.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 47196900 + 19324816 = 6870^2 + 4396^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8315211 + ... + 8315218.

Almost surely, 2^66521716 is an apocalyptic number.

It is an amenable number.

66521716 is a deficient number, since it is larger than the sum of its proper divisors (49891294).

66521716 is a wasteful number, since it uses less digits than its factorization.

66521716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16630433 (or 16630431 counting only the distinct ones).

The product of its digits is 15120, while the sum is 34.

The square root of 66521716 is about 8156.0845998555. The cubic root of 66521716 is about 405.1860467171.

The spelling of 66521716 in words is "sixty-six million, five hundred twenty-one thousand, seven hundred sixteen".