1638540841 has 20 divisors (see below), whose sum is σ = 1917239684. Its totient is φ = 1400263200.

The previous prime is 1638540833. The next prime is 1638540853. The reversal of 1638540841 is 1480458361.

It can be written as a sum of positive squares in 2 ways, for example, as 475458025 + 1163082816 = 21805^2 + 34104^2 .

It is not a de Polignac number, because 1638540841 - 2³ = 1638540833 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1638540794 and 1638540803.

It is not an unprimeable number, because it can be changed into a prime (1638540821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1010011 + ... + 1011631.

Almost surely, 2^1638540841 is an apocalyptic number.

It is an amenable number.

1638540841 is a deficient number, since it is larger than the sum of its proper divisors (278698843).

1638540841 is an frugal number, since it uses more digits than its factorization.

1638540841 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2070 (or 2049 counting only the distinct ones).

The product of its (nonzero) digits is 92160, while the sum is 40.

The square root of 1638540841 is about 40478.8937719400. The cubic root of 1638540841 is about 1178.9238587194.

The spelling of 1638540841 in words is "one billion, six hundred thirty-eight million, five hundred forty thousand, eight hundred forty-one".