991424464209 has 27 divisors (see below), whose sum is σ = 1456186403217. Its totient is φ = 649994918400.

The previous prime is 991424464207. The next prime is 991424464253. The reversal of 991424464209 is 902464424199.

The square root of 991424464209 is 995703.

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

991424464209 is a `hidden beast` number, since 9 + 9 + 1 + 424 + 4 + 6 + 4 + 209 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 128197654209 + 863226810000 = 358047^2 + 929100^2 .

It is not a de Polignac number, because 991424464209 - 2¹ = 991424464207 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (991424464207) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 182210929 + ... + 182216369.

Almost surely, 2^991424464209 is an apocalyptic number.

991424464209 is the 995703-rd square number.

991424464209 is the 497852-nd centered octagonal number.

It is an amenable number.

991424464209 is a deficient number, since it is larger than the sum of its proper divisors (464761939008).

991424464209 is an frugal number, since it uses more digits than its factorization.

991424464209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11010 (or 5505 counting only the distinct ones).

The product of its (nonzero) digits is 4478976, while the sum is 54.

The spelling of 991424464209 in words is "nine hundred ninety-one billion, four hundred twenty-four million, four hundred sixty-four thousand, two hundred nine".