67821821 has 4 divisors (see below), whose sum is σ = 69101532. Its totient is φ = 66542112.

The previous prime is 67821791. The next prime is 67821841. The reversal of 67821821 is 12812876.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 24393721 + 43428100 = 4939^2 + 6590^2 .

It is a cyclic number.

It is not a de Polignac number, because 67821821 - 2⁶ = 67821757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (67821841) 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 in 3 ways as a sum of consecutive naturals, for example, 639776 + ... + 639881.

It is an arithmetic number, because the mean of its divisors is an integer number (17275383).

Almost surely, 2^67821821 is an apocalyptic number.

It is an amenable number.

67821821 is a deficient number, since it is larger than the sum of its proper divisors (1279711).

67821821 is a wasteful number, since it uses less digits than its factorization.

67821821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1279710.

The product of its digits is 10752, while the sum is 35.

The square root of 67821821 is about 8235.4004759939. The cubic root of 67821821 is about 407.8086957979.

The spelling of 67821821 in words is "sixty-seven million, eight hundred twenty-one thousand, eight hundred twenty-one".