1638369 has 6 divisors (see below), whose sum is σ = 2366546. Its totient is φ = 1092240.

The previous prime is 1638353. The next prime is 1638431. The reversal of 1638369 is 9638361.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 1166400 + 471969 = 1080^2 + 687^2 .

It is not a de Polignac number, because 1638369 - 2⁴ = 1638353 is a prime.

It is a super-2 number, since 2×1638369² = 5368505960322, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a plaindrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (1638349) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 91012 + ... + 91029.

2^1638369 is an apocalyptic number.

It is an amenable number.

1638369 is a deficient number, since it is larger than the sum of its proper divisors (728177).

1638369 is a wasteful number, since it uses less digits than its factorization.

1638369 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182047 (or 182044 counting only the distinct ones).

The product of its digits is 23328, while the sum is 36.

The square root of 1638369 is about 1279.9878905677. The cubic root of 1638369 is about 117.8882644298. Note that the first 3 decimals are identical.

The spelling of 1638369 in words is "one million, six hundred thirty-eight thousand, three hundred sixty-nine".