66996621 has 6 divisors (see below), whose sum is σ = 96772910. Its totient is φ = 44664408.

The previous prime is 66996613. The next prime is 66996647. The reversal of 66996621 is 12669966.

It can be written as a sum of positive squares in only one way, i.e., 41139396 + 25857225 = 6414^2 + 5085^2 .

It is not a de Polignac number, because 66996621 - 2³ = 66996613 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66991621) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3722026 + ... + 3722043.

Almost surely, 2^66996621 is an apocalyptic number.

It is an amenable number.

66996621 is a deficient number, since it is larger than the sum of its proper divisors (29776289).

66996621 is a wasteful number, since it uses less digits than its factorization.

66996621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7444075 (or 7444072 counting only the distinct ones).

The product of its digits is 209952, while the sum is 45.

The square root of 66996621 is about 8185.1463639937. The cubic root of 66996621 is about 406.1479820835.

The spelling of 66996621 in words is "sixty-six million, nine hundred ninety-six thousand, six hundred twenty-one".