1687669 has 2 divisors, whose sum is σ = 1687670. Its totient is φ = 1687668.

The previous prime is 1687667. The next prime is 1687729. The reversal of 1687669 is 9667861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1238769 + 448900 = 1113^2 + 670^2 .

It is a cyclic number.

It is not a de Polignac number, because 1687669 - 2¹ = 1687667 is a prime.

It is a super-2 number, since 2×1687669² = 5696453307122, which contains 22 as substring.

Together with 1687667, 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 (1687661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 843834 + 843835.

It is an arithmetic number, because the mean of its divisors is an integer number (843835).

2^1687669 is an apocalyptic number.

It is an amenable number.

1687669 is a deficient number, since it is larger than the sum of its proper divisors (1).

1687669 is an equidigital number, since it uses as much as digits as its factorization.

1687669 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108864, while the sum is 43.

The square root of 1687669 is about 1299.1031521785. The cubic root of 1687669 is about 119.0590531468.

The spelling of 1687669 in words is "one million, six hundred eighty-seven thousand, six hundred sixty-nine".