64680821 has 12 divisors (see below), whose sum is σ = 67359180. Its totient is φ = 62070720.

The previous prime is 64680797. The next prime is 64680841. The reversal of 64680821 is 12808646.

It can be written as a sum of positive squares in 2 ways, for example, as 30924721 + 33756100 = 5561^2 + 5810^2 .

It is not a de Polignac number, because 64680821 - 2⁶ = 64680757 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 (64680841) 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, 282335 + ... + 282563.

It is an arithmetic number, because the mean of its divisors is an integer number (5613265).

Almost surely, 2^64680821 is an apocalyptic number.

It is an amenable number.

64680821 is a deficient number, since it is larger than the sum of its proper divisors (2678359).

64680821 is an equidigital number, since it uses as much as digits as its factorization.

64680821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 436 (or 353 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 35.

The square root of 64680821 is about 8042.4387470468. The cubic root of 64680821 is about 401.4133771141.

The spelling of 64680821 in words is "sixty-four million, six hundred eighty thousand, eight hundred twenty-one".