1638091 has 16 divisors (see below), whose sum is σ = 2064384. Its totient is φ = 1265184.

The previous prime is 1638089. The next prime is 1638097. The reversal of 1638091 is 1908361.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 1638091 - 2¹ = 1638089 is a prime.

It is a zygodrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (1638097) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4086 + ... + 4468.

It is an arithmetic number, because the mean of its divisors is an integer number (129024).

2^1638091 is an apocalyptic number.

1638091 is a deficient number, since it is larger than the sum of its proper divisors (426293).

1638091 is a wasteful number, since it uses less digits than its factorization.

1638091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 450.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 1638091 is about 1279.8792911834. The cubic root of 1638091 is about 117.8815962553.

It can be divided in two parts, 16380 and 91, that added together give a triangular number (16471 = T₁₈₁).

The spelling of 1638091 in words is "one million, six hundred thirty-eight thousand, ninety-one".