1667639 has 2 divisors, whose sum is σ = 1667640. Its totient is φ = 1667638.

The previous prime is 1667629. The next prime is 1667641. The reversal of 1667639 is 9367661.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1667639 - 2⁴ = 1667623 is a prime.

Together with 1667641, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1667609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833819 + 833820.

It is an arithmetic number, because the mean of its divisors is an integer number (833820).

2^1667639 is an apocalyptic number.

1667639 is a deficient number, since it is larger than the sum of its proper divisors (1).

1667639 is an equidigital number, since it uses as much as digits as its factorization.

1667639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40824, while the sum is 38.

The square root of 1667639 is about 1291.3709769079. The cubic root of 1667639 is about 118.5861622402.

The spelling of 1667639 in words is "one million, six hundred sixty-seven thousand, six hundred thirty-nine".