64977721 has 2 divisors, whose sum is σ = 64977722. Its totient is φ = 64977720.

The previous prime is 64977683. The next prime is 64977727. The reversal of 64977721 is 12777946.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 63680400 + 1297321 = 7980^2 + 1139^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-64977721 is a prime.

It is not a weakly prime, because it can be changed into another prime (64977727) 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, 32488860 + 32488861.

It is an arithmetic number, because the mean of its divisors is an integer number (32488861).

Almost surely, 2^64977721 is an apocalyptic number.

It is an amenable number.

64977721 is a deficient number, since it is larger than the sum of its proper divisors (1).

64977721 is an equidigital number, since it uses as much as digits as its factorization.

64977721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 148176, while the sum is 43.

The square root of 64977721 is about 8060.8759449578. The cubic root of 64977721 is about 402.0266333022.

The spelling of 64977721 in words is "sixty-four million, nine hundred seventy-seven thousand, seven hundred twenty-one".