1638864955 has 64 divisors (see below), whose sum is σ = 2484615168. Its totient is φ = 1010257920.

The previous prime is 1638864947. The next prime is 1638864959. The reversal of 1638864955 is 5594688361.

It is not a de Polignac number, because 1638864955 - 2³ = 1638864947 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1638864896 and 1638864905.

It is not an unprimeable number, because it can be changed into a prime (1638864959) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3133324 + ... + 3133846.

It is an arithmetic number, because the mean of its divisors is an integer number (38822112).

Almost surely, 2^1638864955 is an apocalyptic number.

1638864955 is a deficient number, since it is larger than the sum of its proper divisors (845750213).

1638864955 is a wasteful number, since it uses less digits than its factorization.

1638864955 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 716.

The product of its digits is 6220800, while the sum is 55.

The square root of 1638864955 is about 40482.8970677742. The cubic root of 1638864955 is about 1179.0015865218.

The spelling of 1638864955 in words is "one billion, six hundred thirty-eight million, eight hundred sixty-four thousand, nine hundred fifty-five".