67920021 has 12 divisors (see below), whose sum is σ = 105653548. Its totient is φ = 41796864.

The previous prime is 67920019. The next prime is 67920043. The reversal of 67920021 is 12002976.

It can be written as a sum of positive squares in 2 ways, for example, as 26780625 + 41139396 = 5175^2 + 6414^2 .

It is not a de Polignac number, because 67920021 - 2¹ = 67920019 is a prime.

It is a super-2 number, since 2×67920021² = 9226258505280882, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (67920121) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 290140 + ... + 290373.

Almost surely, 2^67920021 is an apocalyptic number.

It is an amenable number.

67920021 is a deficient number, since it is larger than the sum of its proper divisors (37733527).

67920021 is a wasteful number, since it uses less digits than its factorization.

67920021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 580532 (or 580529 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 67920021 is about 8241.3603852762. The cubic root of 67920021 is about 408.0054245242.

Adding to 67920021 its reverse (12002976), we get a palindrome (79922997).

The spelling of 67920021 in words is "sixty-seven million, nine hundred twenty thousand, twenty-one".