1638540842 has 8 divisors (see below), whose sum is σ = 2457983556. Its totient is φ = 819212992.

The previous prime is 1638540833. The next prime is 1638540853. The reversal of 1638540842 is 2480458361.

It can be written as a sum of positive squares in 2 ways, for example, as 1177107481 + 461433361 = 34309^2 + 21481^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 1638540842.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 37328 + ... + 68340.

Almost surely, 2^1638540842 is an apocalyptic number.

1638540842 is a deficient number, since it is larger than the sum of its proper divisors (819442714).

1638540842 is a wasteful number, since it uses less digits than its factorization.

1638540842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57432.

The product of its (nonzero) digits is 184320, while the sum is 41.

The square root of 1638540842 is about 40478.8937842921. The cubic root of 1638540842 is about 1178.9238589593.

The spelling of 1638540842 in words is "one billion, six hundred thirty-eight million, five hundred forty thousand, eight hundred forty-two".