2161651646641 has 4 divisors (see below), whose sum is σ = 2162468291392. Its totient is φ = 2160835001892.

The previous prime is 2161651646629. The next prime is 2161651646657. The reversal of 2161651646641 is 1466461561612.

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 2161651646641 - 2⁹ = 2161651646129 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2161651646741) 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, 408318405 + ... + 408323698.

It is an arithmetic number, because the mean of its divisors is an integer number (540617072848).

Almost surely, 2^{2161651646641} is an apocalyptic number.

It is an amenable number.

2161651646641 is a deficient number, since it is larger than the sum of its proper divisors (816644751).

2161651646641 is an equidigital number, since it uses as much as digits as its factorization.

2161651646641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 816644750.

The product of its digits is 1244160, while the sum is 49.

The spelling of 2161651646641 in words is "two trillion, one hundred sixty-one billion, six hundred fifty-one million, six hundred forty-six thousand, six hundred forty-one".