68021257 has 2 divisors, whose sum is σ = 68021258. Its totient is φ = 68021256.

The previous prime is 68021243. The next prime is 68021263. The reversal of 68021257 is 75212086.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64979721 + 3041536 = 8061^2 + 1744^2 .

It is a cyclic number.

It is not a de Polignac number, because 68021257 - 2¹⁵ = 67988489 is a prime.

It is a Chen prime.

It is the 8248-th Hogben number.

It is not a weakly prime, because it can be changed into another prime (68021287) by changing a digit.

It is a nontrivial repunit in base 8247.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 34010628 + 34010629.

It is an arithmetic number, because the mean of its divisors is an integer number (34010629).

Almost surely, 2^68021257 is an apocalyptic number.

It is an amenable number.

68021257 is a deficient number, since it is larger than the sum of its proper divisors (1).

68021257 is an equidigital number, since it uses as much as digits as its factorization.

68021257 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6720, while the sum is 31.

The square root of 68021257 is about 8247.5000454683. The cubic root of 68021257 is about 408.2080370070.

The spelling of 68021257 in words is "sixty-eight million, twenty-one thousand, two hundred fifty-seven".