11635721161 has 9 divisors (see below), whose sum is σ = 11708335093. Its totient is φ = 11563556800.

The previous prime is 11635721143. The next prime is 11635721171. The reversal of 11635721161 is 16112753611.

The square root of 11635721161 is 107869.

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

It can be written as a sum of positive squares in 4 ways, for example, as 293471161 + 11342250000 = 17131^2 + 106500^2 .

It is not a de Polignac number, because 11635721161 - 2¹⁹ = 11635196873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11635721131) 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, 29016561 + ... + 29016961.

Almost surely, 2^11635721161 is an apocalyptic number.

11635721161 is the 107869-th square number.

11635721161 is the 53935-th centered octagonal number.

It is an amenable number.

11635721161 is a deficient number, since it is larger than the sum of its proper divisors (72613932).

11635721161 is an frugal number, since it uses more digits than its factorization.

11635721161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1340 (or 670 counting only the distinct ones).

The product of its digits is 7560, while the sum is 34.

The spelling of 11635721161 in words is "eleven billion, six hundred thirty-five million, seven hundred twenty-one thousand, one hundred sixty-one".