1638365 has 4 divisors (see below), whose sum is σ = 1966044. Its totient is φ = 1310688.

The previous prime is 1638353. The next prime is 1638431. The reversal of 1638365 is 5638361.

1638365 = 738² + 739² + 740².

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 964324 + 674041 = 982^2 + 821^2 .

It is a cyclic number.

It is not a de Polignac number, because 1638365 - 2⁴ = 1638349 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 163832 + ... + 163841.

It is an arithmetic number, because the mean of its divisors is an integer number (491511).

2^1638365 is an apocalyptic number.

It is an amenable number.

1638365 is a deficient number, since it is larger than the sum of its proper divisors (327679).

1638365 is an equidigital number, since it uses as much as digits as its factorization.

1638365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 327678.

The product of its digits is 12960, while the sum is 32.

The square root of 1638365 is about 1279.9863280520. The cubic root of 1638365 is about 117.8881684902. Note that the first 3 decimals are identical.

The spelling of 1638365 in words is "one million, six hundred thirty-eight thousand, three hundred sixty-five".