2208311909521 has 9 divisors (see below), whose sum is σ = 2224753735099. Its totient is φ = 2191990743184.

The previous prime is 2208311909513. The next prime is 2208311909561. The reversal of 2208311909521 is 1259091138022.

The square root of 2208311909521 is 1486039.

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

It can be written as a sum of positive squares in only one way, i.e., 1297172934225 + 911138975296 = 1138935^2 + 954536^2 .

It is not a de Polignac number, because 2208311909521 - 2³ = 2208311909513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2208311909561) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 203581920 + ... + 203592766.

Almost surely, 2^{2208311909521} is an apocalyptic number.

2208311909521 is the 1486039-th square number.

2208311909521 is the 743020-th centered octagonal number.

It is an amenable number.

2208311909521 is a deficient number, since it is larger than the sum of its proper divisors (16441825578).

2208311909521 is an frugal number, since it uses more digits than its factorization.

2208311909521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21968 (or 10984 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 43.

The spelling of 2208311909521 in words is "two trillion, two hundred eight billion, three hundred eleven million, nine hundred nine thousand, five hundred twenty-one".