1638649 has 2 divisors, whose sum is σ = 1638650. Its totient is φ = 1638648.

The previous prime is 1638641. The next prime is 1638653. The reversal of 1638649 is 9468361.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1452025 + 186624 = 1205^2 + 432^2 .

It is a cyclic number.

It is not a de Polignac number, because 1638649 - 2³ = 1638641 is a prime.

It is not a weakly prime, because it can be changed into another prime (1638641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 819324 + 819325.

It is an arithmetic number, because the mean of its divisors is an integer number (819325).

2^1638649 is an apocalyptic number.

It is an amenable number.

1638649 is a deficient number, since it is larger than the sum of its proper divisors (1).

1638649 is an equidigital number, since it uses as much as digits as its factorization.

1638649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 37.

The square root of 1638649 is about 1280.0972619297. The cubic root of 1638649 is about 117.8949798144.

The spelling of 1638649 in words is "one million, six hundred thirty-eight thousand, six hundred forty-nine".