66999213 has 6 divisors (see below), whose sum is σ = 96776654. Its totient is φ = 44666136.

The previous prime is 66999211. The next prime is 66999223. The reversal of 66999213 is 31299966.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 43204329 + 23794884 = 6573^2 + 4878^2 .

It is not a de Polignac number, because 66999213 - 2¹ = 66999211 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66999211) 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, 3722170 + ... + 3722187.

Almost surely, 2^66999213 is an apocalyptic number.

It is an amenable number.

66999213 is a deficient number, since it is larger than the sum of its proper divisors (29777441).

66999213 is a wasteful number, since it uses less digits than its factorization.

66999213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7444363 (or 7444360 counting only the distinct ones).

The product of its digits is 157464, while the sum is 45.

The square root of 66999213 is about 8185.3046980549. The cubic root of 66999213 is about 406.1532197705.

The spelling of 66999213 in words is "sixty-six million, nine hundred ninety-nine thousand, two hundred thirteen".