1638645 has 16 divisors (see below), whose sum is σ = 2712960. Its totient is φ = 843584.

The previous prime is 1638641. The next prime is 1638649. The reversal of 1638645 is 5468361.

It is an interprime number because it is at equal distance from previous prime (1638641) and next prime (1638649).

It is a cyclic number.

It is not a de Polignac number, because 1638645 - 2² = 1638641 is a prime.

1638645 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1638641) 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, 1449 + ... + 2318.

It is an arithmetic number, because the mean of its divisors is an integer number (169560).

2^1638645 is an apocalyptic number.

1638645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1638645 is a deficient number, since it is larger than the sum of its proper divisors (1074315).

1638645 is a wasteful number, since it uses less digits than its factorization.

1638645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3804.

The product of its digits is 17280, while the sum is 33.

The square root of 1638645 is about 1280.0956995475. The cubic root of 1638645 is about 117.8948838857.

The spelling of 1638645 in words is "one million, six hundred thirty-eight thousand, six hundred forty-five".