64040021 has 2 divisors, whose sum is σ = 64040022. Its totient is φ = 64040020.

The previous prime is 64039999. The next prime is 64040047. The reversal of 64040021 is 12004046.

64040021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43744996 + 20295025 = 6614^2 + 4505^2 .

It is a cyclic number.

It is not a de Polignac number, because 64040021 - 2¹⁸ = 63777877 is a prime.

It is a super-2 number, since 2×64040021² = 8202248579360882, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64040521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32020010 + 32020011.

It is an arithmetic number, because the mean of its divisors is an integer number (32020011).

Almost surely, 2^64040021 is an apocalyptic number.

It is an amenable number.

64040021 is a deficient number, since it is larger than the sum of its proper divisors (1).

64040021 is an equidigital number, since it uses as much as digits as its factorization.

64040021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 64040021 is about 8002.5009215870. The cubic root of 64040021 is about 400.0833597100.

Adding to 64040021 its reverse (12004046), we get a palindrome (76044067).

The spelling of 64040021 in words is "sixty-four million, forty thousand, twenty-one".