1641541561 has 4 divisors (see below), whose sum is σ = 1790772624. Its totient is φ = 1492310500.

The previous prime is 1641541529. The next prime is 1641541571. The reversal of 1641541561 is 1651451461.

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 1641541561 - 2⁵ = 1641541529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1641541571) 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, 74615515 + ... + 74615536.

It is an arithmetic number, because the mean of its divisors is an integer number (447693156).

Almost surely, 2^1641541561 is an apocalyptic number.

1641541561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1641541561 is a deficient number, since it is larger than the sum of its proper divisors (149231063).

1641541561 is a wasteful number, since it uses less digits than its factorization.

1641541561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149231062.

The product of its digits is 14400, while the sum is 34.

The square root of 1641541561 is about 40515.9420598855. The cubic root of 1641541561 is about 1179.6430886958.

The spelling of 1641541561 in words is "one billion, six hundred forty-one million, five hundred forty-one thousand, five hundred sixty-one".