66621651 has 8 divisors (see below), whose sum is σ = 90154944. Its totient is φ = 43751400.

The previous prime is 66621649. The next prime is 66621661. The reversal of 66621651 is 15612666.

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

It is not a de Polignac number, because 66621651 - 2¹ = 66621649 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (66621641) 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, 165525 + ... + 165926.

It is an arithmetic number, because the mean of its divisors is an integer number (11269368).

Almost surely, 2^66621651 is an apocalyptic number.

66621651 is a deficient number, since it is larger than the sum of its proper divisors (23533293).

66621651 is a wasteful number, since it uses less digits than its factorization.

66621651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331521.

The product of its digits is 12960, while the sum is 33.

The square root of 66621651 is about 8162.2087084318. The cubic root of 66621651 is about 405.3888476962.

The spelling of 66621651 in words is "sixty-six million, six hundred twenty-one thousand, six hundred fifty-one".