66821373 has 12 divisors (see below), whose sum is σ = 102197628. Its totient is φ = 41927040.

The previous prime is 66821369. The next prime is 66821389. The reversal of 66821373 is 37312866.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 57198969 + 9622404 = 7563^2 + 3102^2 .

It is not a de Polignac number, because 66821373 - 2² = 66821369 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66821303) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 218218 + ... + 218523.

It is an arithmetic number, because the mean of its divisors is an integer number (8516469).

Almost surely, 2^66821373 is an apocalyptic number.

It is an amenable number.

66821373 is a deficient number, since it is larger than the sum of its proper divisors (35376255).

66821373 is a wasteful number, since it uses less digits than its factorization.

66821373 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 436764 (or 436761 counting only the distinct ones).

The product of its digits is 36288, while the sum is 36.

The square root of 66821373 is about 8174.4341088543. The cubic root of 66821373 is about 405.7935424541.

The spelling of 66821373 in words is "sixty-six million, eight hundred twenty-one thousand, three hundred seventy-three".