66381623 has 24 divisors (see below), whose sum is σ = 85100544. Its totient is φ = 51198000.

The previous prime is 66381619. The next prime is 66381647. The reversal of 66381623 is 32618366.

It is not a de Polignac number, because 66381623 - 2² = 66381619 is a prime.

It is a super-2 number, since 2×66381623² = 8813039744228258, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66387623) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 57098 + ... + 58248.

It is an arithmetic number, because the mean of its divisors is an integer number (3545856).

Almost surely, 2^66381623 is an apocalyptic number.

66381623 is a deficient number, since it is larger than the sum of its proper divisors (18718921).

66381623 is a wasteful number, since it uses less digits than its factorization.

66381623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1283 (or 1276 counting only the distinct ones).

The product of its digits is 31104, while the sum is 35.

The square root of 66381623 is about 8147.4918226409. The cubic root of 66381623 is about 404.9014097264.

Adding to 66381623 its reverse (32618366), we get a palindrome (98999989).

The spelling of 66381623 in words is "sixty-six million, three hundred eighty-one thousand, six hundred twenty-three".