66821013 has 24 divisors (see below), whose sum is σ = 110534528. Its totient is φ = 38104992.

The previous prime is 66821009. The next prime is 66821023. The reversal of 66821013 is 31012866.

It is not a de Polignac number, because 66821013 - 2² = 66821009 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 (66821023) 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, 45456 + ... + 46902.

Almost surely, 2^66821013 is an apocalyptic number.

66821013 is a gapful number since it is divisible by the number (63) formed by its first and last digit.

It is an amenable number.

66821013 is a deficient number, since it is larger than the sum of its proper divisors (43713515).

66821013 is a wasteful number, since it uses less digits than its factorization.

66821013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2193 (or 2190 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 66821013 is about 8174.4120889517. The cubic root of 66821013 is about 405.7928137155.

Adding to 66821013 its reverse (31012866), we get a palindrome (97833879).

The spelling of 66821013 in words is "sixty-six million, eight hundred twenty-one thousand, thirteen".