64943821 has 2 divisors, whose sum is σ = 64943822. Its totient is φ = 64943820.

The previous prime is 64943807. The next prime is 64943873. The reversal of 64943821 is 12834946.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 38266596 + 26677225 = 6186^2 + 5165^2 .

It is a cyclic number.

It is not a de Polignac number, because 64943821 - 2⁷ = 64943693 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64943321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32471910 + 32471911.

It is an arithmetic number, because the mean of its divisors is an integer number (32471911).

Almost surely, 2^64943821 is an apocalyptic number.

It is an amenable number.

64943821 is a deficient number, since it is larger than the sum of its proper divisors (1).

64943821 is an equidigital number, since it uses as much as digits as its factorization.

64943821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 41472, while the sum is 37.

The square root of 64943821 is about 8058.7729214813. The cubic root of 64943821 is about 401.9567063926.

The spelling of 64943821 in words is "sixty-four million, nine hundred forty-three thousand, eight hundred twenty-one".