2161651564421 has 16 divisors (see below), whose sum is σ = 2257884969600. Its totient is φ = 2065606507008.

The previous prime is 2161651564399. The next prime is 2161651564433. The reversal of 2161651564421 is 1244651561612.

It is a cyclic number.

It is not a de Polignac number, because 2161651564421 - 2¹⁰ = 2161651563397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2161651564921) 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, 129068570 + ... + 129085316.

It is an arithmetic number, because the mean of its divisors is an integer number (141117810600).

Almost surely, 2^{2161651564421} is an apocalyptic number.

It is an amenable number.

2161651564421 is a deficient number, since it is larger than the sum of its proper divisors (96233405179).

2161651564421 is a wasteful number, since it uses less digits than its factorization.

2161651564421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22028.

The product of its digits is 345600, while the sum is 44.

The spelling of 2161651564421 in words is "two trillion, one hundred sixty-one billion, six hundred fifty-one million, five hundred sixty-four thousand, four hundred twenty-one".