1161661521 has 16 divisors (see below), whose sum is σ = 1555616000. Its totient is φ = 771083280.

The previous prime is 1161661517. The next prime is 1161661537. The reversal of 1161661521 is 1251661611.

It is not a de Polignac number, because 1161661521 - 2² = 1161661517 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1161661591) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1033866 + ... + 1034988.

It is an arithmetic number, because the mean of its divisors is an integer number (97226000).

Almost surely, 2^1161661521 is an apocalyptic number.

It is an amenable number.

1161661521 is a deficient number, since it is larger than the sum of its proper divisors (393954479).

1161661521 is a wasteful number, since it uses less digits than its factorization.

1161661521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2316.

The product of its digits is 2160, while the sum is 30.

The square root of 1161661521 is about 34083.1559718287. The cubic root of 1161661521 is about 1051.2189987667.

It can be divided in two parts, 11616 and 61521, that added together give a palindrome (73137).

The spelling of 1161661521 in words is "one billion, one hundred sixty-one million, six hundred sixty-one thousand, five hundred twenty-one".