637916897809 has 3 divisors (see below), whose sum is σ = 637917696507. Its totient is φ = 637916099112.

The previous prime is 637916897771. The next prime is 637916897867. The reversal of 637916897809 is 908798619736.

The square root of 637916897809 is 798697.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 185429278225 + 452487619584 = 430615^2 + 672672^2 .

It is not a de Polignac number, because 637916897809 - 2²⁹ = 637380026897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (637916897309) 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 2 ways as a sum of consecutive naturals, for example, 399349 + ... + 1198045.

It is an arithmetic number, because the mean of its divisors is an integer number (212639232169).

Almost surely, 2^637916897809 is an apocalyptic number.

637916897809 is the 798697-th square number.

637916897809 is the 399349-th centered octagonal number.

It is an amenable number.

637916897809 is a deficient number, since it is larger than the sum of its proper divisors (798698).

637916897809 is an frugal number, since it uses more digits than its factorization.

637916897809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1597394 (or 798697 counting only the distinct ones).

The product of its (nonzero) digits is 246903552, while the sum is 73.

The spelling of 637916897809 in words is "six hundred thirty-seven billion, nine hundred sixteen million, eight hundred ninety-seven thousand, eight hundred nine".