67686021 has 18 divisors (see below), whose sum is σ = 105870258. Its totient is φ = 41652000.

The previous prime is 67686019. The next prime is 67686023. The reversal of 67686021 is 12068676.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (67686019) and next prime (67686023).

It can be written as a sum of positive squares in 3 ways, for example, as 216225 + 67469796 = 465^2 + 8214^2 .

It is not a de Polignac number, because 67686021 - 2¹ = 67686019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (67686023) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 20730 + ... + 23771.

It is an arithmetic number, because the mean of its divisors is an integer number (5881681).

Almost surely, 2^67686021 is an apocalyptic number.

It is an amenable number.

67686021 is a deficient number, since it is larger than the sum of its proper divisors (38184237).

67686021 is a wasteful number, since it uses less digits than its factorization.

67686021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44533 (or 44517 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 67686021 is about 8227.1514511403. The cubic root of 67686021 is about 407.5363280747.

The spelling of 67686021 in words is "sixty-seven million, six hundred eighty-six thousand, twenty-one".