1638869 has 2 divisors, whose sum is σ = 1638870. Its totient is φ = 1638868.

The previous prime is 1638821. The next prime is 1638899. The reversal of 1638869 is 9688361.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1592644 + 46225 = 1262^2 + 215^2 .

It is an emirp because it is prime and its reverse (9688361) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1638869 is a prime.

It is a super-2 number, since 2×1638869² = 5371783198322, which contains 22 as substring.

It is a Chen prime.

It is a plaindrome in base 15.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1638809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 819434 + 819435.

It is an arithmetic number, because the mean of its divisors is an integer number (819435).

2^1638869 is an apocalyptic number.

It is an amenable number.

1638869 is a deficient number, since it is larger than the sum of its proper divisors (1).

1638869 is an equidigital number, since it uses as much as digits as its factorization.

1638869 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 62208, while the sum is 41.

The square root of 1638869 is about 1280.1831900162. The cubic root of 1638869 is about 117.9002556514.

The spelling of 1638869 in words is "one million, six hundred thirty-eight thousand, eight hundred sixty-nine".