1638401 has 8 divisors (see below), whose sum is σ = 1701000. Its totient is φ = 1576960.

The previous prime is 1638353. The next prime is 1638431. The reversal of 1638401 is 1048361.

It is a Cunningham number, because it is equal to 1280²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 1 + 1638400 = 1^2 + 1280^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1638401 - 2¹⁸ = 1376257 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (1638431) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3425 + ... + 3873.

It is an arithmetic number, because the mean of its divisors is an integer number (212625).

It is a Proth number, since it is equal to 25 ⋅ 2¹⁶ + 1 and 25 < 2¹⁶.

2^1638401 is an apocalyptic number.

It is an amenable number.

1638401 is a deficient number, since it is larger than the sum of its proper divisors (62599).

1638401 is an equidigital number, since it uses as much as digits as its factorization.

1638401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 579.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 1638401 is about 1280.0003906249. Note that the first 3 decimals coincide. The cubic root of 1638401 is about 117.8890319411.

It can be divided in two parts, 16 and 38401, that multiplied together give a palindrome (614416).

The spelling of 1638401 in words is "one million, six hundred thirty-eight thousand, four hundred one".