6721669 has 2 divisors, whose sum is σ = 6721670. Its totient is φ = 6721668.

The previous prime is 6721667. The next prime is 6721691. The reversal of 6721669 is 9661276.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5428900 + 1292769 = 2330^2 + 1137^2 .

It is a cyclic number.

It is not a de Polignac number, because 6721669 - 2¹ = 6721667 is a prime.

It is a super-2 number, since 2×6721669² = 90361668291122, which contains 22 as substring.

Together with 6721667, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6721661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3360834 + 3360835.

It is an arithmetic number, because the mean of its divisors is an integer number (3360835).

Almost surely, 2^6721669 is an apocalyptic number.

It is an amenable number.

6721669 is a deficient number, since it is larger than the sum of its proper divisors (1).

6721669 is an equidigital number, since it uses as much as digits as its factorization.

6721669 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27216, while the sum is 37.

The square root of 6721669 is about 2592.6181747415. The cubic root of 6721669 is about 188.7233806005.

It can be divided in two parts, 67 and 21669, that added together give a triangular number (21736 = T₂₀₈).

The spelling of 6721669 in words is "six million, seven hundred twenty-one thousand, six hundred sixty-nine".