2179781746561 has 4 divisors (see below), whose sum is σ = 2179996873812. Its totient is φ = 2179566619312.

The previous prime is 2179781746547. The next prime is 2179781746601. The reversal of 2179781746561 is 1656471879712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1667778530625 + 512003215936 = 1291425^2 + 715544^2 .

It is a cyclic number.

It is not a de Polignac number, because 2179781746561 - 2⁷ = 2179781746433 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2179781746493 and 2179781746502.

It is not an unprimeable number, because it can be changed into a prime (2179781746531) 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, 107548426 + ... + 107568691.

It is an arithmetic number, because the mean of its divisors is an integer number (544999218453).

Almost surely, 2^{2179781746561} is an apocalyptic number.

It is an amenable number.

2179781746561 is a deficient number, since it is larger than the sum of its proper divisors (215127251).

2179781746561 is a wasteful number, since it uses less digits than its factorization.

2179781746561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215127250.

The product of its digits is 35562240, while the sum is 64.

The spelling of 2179781746561 in words is "two trillion, one hundred seventy-nine billion, seven hundred eighty-one million, seven hundred forty-six thousand, five hundred sixty-one".