66642521 has 8 divisors (see below), whose sum is σ = 73008000. Its totient is φ = 60328240.

The previous prime is 66642509. The next prime is 66642553. The reversal of 66642521 is 12524666.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66642521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66642581) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10046 + ... + 15303.

It is an arithmetic number, because the mean of its divisors is an integer number (9126000).

Almost surely, 2^66642521 is an apocalyptic number.

It is an amenable number.

66642521 is a deficient number, since it is larger than the sum of its proper divisors (6365479).

66642521 is a wasteful number, since it uses less digits than its factorization.

66642521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25599.

The product of its digits is 17280, while the sum is 32.

The square root of 66642521 is about 8163.4870612992. The cubic root of 66642521 is about 405.4311741864.

The spelling of 66642521 in words is "sixty-six million, six hundred forty-two thousand, five hundred twenty-one".