647537261809 has 3 divisors (see below), whose sum is σ = 647538066507. Its totient is φ = 647536457112.

The previous prime is 647537261779. The next prime is 647537261857. The reversal of 647537261809 is 908162735746.

The square root of 647537261809 is 804697.

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., 613190794225 + 34346467584 = 783065^2 + 185328^2 .

It is not a de Polignac number, because 647537261809 - 2²¹ = 647535164657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (647537261009) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 402349 + ... + 1207045.

It is an arithmetic number, because the mean of its divisors is an integer number (215846022169).

It is a 2-persistent number, because it is pandigital, and so is 2⋅647537261809 = 1295074523618, but 3⋅647537261809 = 1942611785427 is not.

Almost surely, 2^647537261809 is an apocalyptic number.

647537261809 is the 804697-th square number.

647537261809 is the 402349-th centered octagonal number.

It is an amenable number.

647537261809 is a deficient number, since it is larger than the sum of its proper divisors (804698).

647537261809 is an frugal number, since it uses more digits than its factorization.

647537261809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1609394 (or 804697 counting only the distinct ones).

The product of its (nonzero) digits is 15240960, while the sum is 58.

The spelling of 647537261809 in words is "six hundred forty-seven billion, five hundred thirty-seven million, two hundred sixty-one thousand, eight hundred nine".