2156443221561 has 16 divisors (see below), whose sum is σ = 2881318353984. Its totient is φ = 1434599921664.

The previous prime is 2156443221553. The next prime is 2156443221593. The reversal of 2156443221561 is 1651223446512.

It is not a de Polignac number, because 2156443221561 - 2³ = 2156443221553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2156443221461) 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, 5753841 + ... + 6117153.

It is an arithmetic number, because the mean of its divisors is an integer number (180082397124).

Almost surely, 2^{2156443221561} is an apocalyptic number.

It is an amenable number.

2156443221561 is a deficient number, since it is larger than the sum of its proper divisors (724875132423).

2156443221561 is a wasteful number, since it uses less digits than its factorization.

2156443221561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 367480.

The product of its digits is 345600, while the sum is 42.

The spelling of 2156443221561 in words is "two trillion, one hundred fifty-six billion, four hundred forty-three million, two hundred twenty-one thousand, five hundred sixty-one".