1661136541 has 4 divisors (see below), whose sum is σ = 1748564800. Its totient is φ = 1573708284.

The previous prime is 1661136527. The next prime is 1661136551. The reversal of 1661136541 is 1456311661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1661136541 - 2⁵ = 1661136509 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1661136497 and 1661136506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661136511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43714101 + ... + 43714138.

It is an arithmetic number, because the mean of its divisors is an integer number (437141200).

Almost surely, 2^1661136541 is an apocalyptic number.

It is an amenable number.

1661136541 is a deficient number, since it is larger than the sum of its proper divisors (87428259).

1661136541 is an equidigital number, since it uses as much as digits as its factorization.

1661136541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87428258.

The product of its digits is 12960, while the sum is 34.

The square root of 1661136541 is about 40757.0428392444. The cubic root of 1661136541 is about 1184.3183106475.

The spelling of 1661136541 in words is "one billion, six hundred sixty-one million, one hundred thirty-six thousand, five hundred forty-one".