1638121 has 2 divisors, whose sum is σ = 1638122. Its totient is φ = 1638120.

The previous prime is 1638107. The next prime is 1638127. The reversal of 1638121 is 1218361.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1525225 + 112896 = 1235^2 + 336^2 .

It is a cyclic number.

It is not a de Polignac number, because 1638121 - 2⁵ = 1638089 is a prime.

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

It is a junction number, because it is equal to n+sod(n) for n = 1638092 and 1638101.

It is not a weakly prime, because it can be changed into another prime (1638127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 819060 + 819061.

It is an arithmetic number, because the mean of its divisors is an integer number (819061).

2^1638121 is an apocalyptic number.

It is an amenable number.

1638121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1638121 is an equidigital number, since it uses as much as digits as its factorization.

1638121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 288, while the sum is 22.

The square root of 1638121 is about 1279.8910109849. The cubic root of 1638121 is about 117.8823158788.

The spelling of 1638121 in words is "one million, six hundred thirty-eight thousand, one hundred twenty-one".