67856521 has 2 divisors, whose sum is σ = 67856522. Its totient is φ = 67856520.

The previous prime is 67856519. The next prime is 67856561. The reversal of 67856521 is 12565876.

It is an a-pointer prime, because the next prime (67856561) can be obtained adding 67856521 to its sum of digits (40).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55711296 + 12145225 = 7464^2 + 3485^2 .

It is a cyclic number.

It is not a de Polignac number, because 67856521 - 2¹ = 67856519 is a prime.

Together with 67856519, it forms a pair of twin primes.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (67856561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33928260 + 33928261.

It is an arithmetic number, because the mean of its divisors is an integer number (33928261).

Almost surely, 2^67856521 is an apocalyptic number.

It is an amenable number.

67856521 is a deficient number, since it is larger than the sum of its proper divisors (1).

67856521 is an equidigital number, since it uses as much as digits as its factorization.

67856521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 100800, while the sum is 40.

The square root of 67856521 is about 8237.5069650957. The cubic root of 67856521 is about 407.8782336391.

The spelling of 67856521 in words is "sixty-seven million, eight hundred fifty-six thousand, five hundred twenty-one".