1638634 has 4 divisors (see below), whose sum is σ = 2457954. Its totient is φ = 819316.

The previous prime is 1638599. The next prime is 1638641. The reversal of 1638634 is 4368361.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 4368361 = 191 ⋅22871.

It can be written as a sum of positive squares in only one way, i.e., 1476225 + 162409 = 1215^2 + 403^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 1638596 and 1638605.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 409657 + ... + 409660.

2^1638634 is an apocalyptic number.

1638634 is a deficient number, since it is larger than the sum of its proper divisors (819320).

1638634 is an equidigital number, since it uses as much as digits as its factorization.

1638634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 819319.

The product of its digits is 10368, while the sum is 31.

The square root of 1638634 is about 1280.0914029865. The cubic root of 1638634 is about 117.8946200811.

The spelling of 1638634 in words is "one million, six hundred thirty-eight thousand, six hundred thirty-four".