67778521 has 2 divisors, whose sum is σ = 67778522. Its totient is φ = 67778520.

The previous prime is 67778419. The next prime is 67778533. The reversal of 67778521 is 12587776.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61402896 + 6375625 = 7836^2 + 2525^2 .

It is a cyclic number.

It is not a de Polignac number, because 67778521 - 2⁷ = 67778393 is a prime.

It is not a weakly prime, because it can be changed into another prime (67778591) 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, 33889260 + 33889261.

It is an arithmetic number, because the mean of its divisors is an integer number (33889261).

Almost surely, 2^67778521 is an apocalyptic number.

It is an amenable number.

67778521 is a deficient number, since it is larger than the sum of its proper divisors (1).

67778521 is an equidigital number, since it uses as much as digits as its factorization.

67778521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 164640, while the sum is 43.

The square root of 67778521 is about 8232.7711616442. The cubic root of 67778521 is about 407.7218905216.

The spelling of 67778521 in words is "sixty-seven million, seven hundred seventy-eight thousand, five hundred twenty-one".