1638555897 has 32 divisors (see below), whose sum is σ = 2571212160. Its totient is φ = 916997120.

The previous prime is 1638555889. The next prime is 1638555899. The reversal of 1638555897 is 7985558361.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 1638555897 - 2³ = 1638555889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1638555899) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2179 + ... + 57287.

It is an arithmetic number, because the mean of its divisors is an integer number (80350380).

Almost surely, 2^1638555897 is an apocalyptic number.

1638555897 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

1638555897 is a deficient number, since it is larger than the sum of its proper divisors (932656263).

1638555897 is a wasteful number, since it uses less digits than its factorization.

1638555897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55193.

The product of its digits is 9072000, while the sum is 57.

The square root of 1638555897 is about 40479.0797449744. The cubic root of 1638555897 is about 1178.9274696198.

The spelling of 1638555897 in words is "one billion, six hundred thirty-eight million, five hundred fifty-five thousand, eight hundred ninety-seven".