1638121164 has 12 divisors (see below), whose sum is σ = 3822282744. Its totient is φ = 546040384.

The previous prime is 1638121141. The next prime is 1638121183. The reversal of 1638121164 is 4611218361.

It is a tau number, because it is divible by the number of its divisors (12).

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 3 ways as a sum of consecutive naturals, for example, 68255037 + ... + 68255060.

It is an arithmetic number, because the mean of its divisors is an integer number (318523562).

Almost surely, 2^1638121164 is an apocalyptic number.

It is an amenable number.

1638121164 is an abundant number, since it is smaller than the sum of its proper divisors (2184161580).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1638121164 is a wasteful number, since it uses less digits than its factorization.

1638121164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136510104 (or 136510102 counting only the distinct ones).

The product of its digits is 6912, while the sum is 33.

The square root of 1638121164 is about 40473.7095408859. The cubic root of 1638121164 is about 1178.8231981270.

The spelling of 1638121164 in words is "one billion, six hundred thirty-eight million, one hundred twenty-one thousand, one hundred sixty-four".