66621623 has 4 divisors (see below), whose sum is σ = 70540560. Its totient is φ = 62702688.

The previous prime is 66621617. The next prime is 66621641. The reversal of 66621623 is 32612666.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66621623 - 2⁶ = 66621559 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66621623.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66629623) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1959443 + ... + 1959476.

It is an arithmetic number, because the mean of its divisors is an integer number (17635140).

Almost surely, 2^66621623 is an apocalyptic number.

66621623 is a deficient number, since it is larger than the sum of its proper divisors (3918937).

66621623 is a wasteful number, since it uses less digits than its factorization.

66621623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3918936.

The product of its digits is 15552, while the sum is 32.

The square root of 66621623 is about 8162.2069932096. The cubic root of 66621623 is about 405.3887909035.

The spelling of 66621623 in words is "sixty-six million, six hundred twenty-one thousand, six hundred twenty-three".