197638809 has 4 divisors (see below), whose sum is σ = 263518416. Its totient is φ = 131759204.

The previous prime is 197638801. The next prime is 197638823. The reversal of 197638809 is 908836791.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 197638809 - 2³ = 197638801 is a prime.

It is a super-2 number, since 2×197638809² = 78122197645876962, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (197638801) by changing a digit.

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, 32939799 + ... + 32939804.

It is an arithmetic number, because the mean of its divisors is an integer number (65879604).

Almost surely, 2^197638809 is an apocalyptic number.

It is an amenable number.

197638809 is a deficient number, since it is larger than the sum of its proper divisors (65879607).

197638809 is an equidigital number, since it uses as much as digits as its factorization.

197638809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65879606.

The product of its (nonzero) digits is 653184, while the sum is 51.

The square root of 197638809 is about 14058.4070577004. The cubic root of 197638809 is about 582.4930429520.

The spelling of 197638809 in words is "one hundred ninety-seven million, six hundred thirty-eight thousand, eight hundred nine".