1661232011 has 4 divisors (see below), whose sum is σ = 1661331672. Its totient is φ = 1661132352.

The previous prime is 1661232007. The next prime is 1661232037. The reversal of 1661232011 is 1102321661.

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 is a cyclic number.

It is not a de Polignac number, because 1661232011 - 2² = 1661232007 is a prime.

It is a super-3 number, since 3×1661232011³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1661222011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18086 + ... + 60411.

It is an arithmetic number, because the mean of its divisors is an integer number (415332918).

Almost surely, 2^1661232011 is an apocalyptic number.

1661232011 is a deficient number, since it is larger than the sum of its proper divisors (99661).

1661232011 is an equidigital number, since it uses as much as digits as its factorization.

1661232011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99660.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 1661232011 is about 40758.2140310392. The cubic root of 1661232011 is about 1184.3409988694.

Adding to 1661232011 its reverse (1102321661), we get a palindrome (2763553672).

The spelling of 1661232011 in words is "one billion, six hundred sixty-one million, two hundred thirty-two thousand, eleven".