1638881 has 4 divisors (see below), whose sum is σ = 1643952. Its totient is φ = 1633812.

The previous prime is 1638869. The next prime is 1638899. The reversal of 1638881 is 1888361.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1638881 - 2¹⁸ = 1376737 is a prime.

It is a super-2 number, since 2×1638881² = 5371861864322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1638821) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2015 + ... + 2708.

It is an arithmetic number, because the mean of its divisors is an integer number (410988).

2^1638881 is an apocalyptic number.

It is an amenable number.

1638881 is a deficient number, since it is larger than the sum of its proper divisors (5071).

1638881 is an equidigital number, since it uses as much as digits as its factorization.

1638881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5070.

The product of its digits is 9216, while the sum is 35.

The square root of 1638881 is about 1280.1878768368. The cubic root of 1638881 is about 117.9005434107.

The spelling of 1638881 in words is "one million, six hundred thirty-eight thousand, eight hundred eighty-one".