65819921 has 2 divisors, whose sum is σ = 65819922. Its totient is φ = 65819920.

The previous prime is 65819899. The next prime is 65819927. The reversal of 65819921 is 12991856.

It is a happy number.

65819921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 57760000 + 8059921 = 7600^2 + 2839^2 .

It is a cyclic number.

It is not a de Polignac number, because 65819921 - 2¹⁰ = 65818897 is a prime.

It is not a weakly prime, because it can be changed into another prime (65819927) 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, 32909960 + 32909961.

It is an arithmetic number, because the mean of its divisors is an integer number (32909961).

Almost surely, 2^65819921 is an apocalyptic number.

It is an amenable number.

65819921 is a deficient number, since it is larger than the sum of its proper divisors (1).

65819921 is an equidigital number, since it uses as much as digits as its factorization.

65819921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 41.

The square root of 65819921 is about 8112.9477380296. The cubic root of 65819921 is about 403.7561205768.

The spelling of 65819921 in words is "sixty-five million, eight hundred nineteen thousand, nine hundred twenty-one".