1638120975 has 24 divisors (see below), whose sum is σ = 2710278912. Its totient is φ = 873045600.

The previous prime is 1638120959. The next prime is 1638121007. The reversal of 1638120975 is 5790218361.

It is not a de Polignac number, because 1638120975 - 2⁴ = 1638120959 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 110874 + ... + 124776.

It is an arithmetic number, because the mean of its divisors is an integer number (112928288).

Almost surely, 2^1638120975 is an apocalyptic number.

1638120975 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1638120975 is a deficient number, since it is larger than the sum of its proper divisors (1072157937).

1638120975 is a wasteful number, since it uses less digits than its factorization.

1638120975 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15487 (or 15482 counting only the distinct ones).

The product of its (nonzero) digits is 90720, while the sum is 42.

The square root of 1638120975 is about 40473.7072060369. The cubic root of 1638120975 is about 1178.8231527910.

The spelling of 1638120975 in words is "one billion, six hundred thirty-eight million, one hundred twenty thousand, nine hundred seventy-five".