20123671561 has 32 divisors (see below), whose sum is σ = 24312499200. Its totient is φ = 16292162880.

The previous prime is 20123671559. The next prime is 20123671637. The reversal of 20123671561 is 16517632102.

It is not a de Polignac number, because 20123671561 - 2¹ = 20123671559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20123671961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2523166 + ... + 2531128.

It is an arithmetic number, because the mean of its divisors is an integer number (759765600).

Almost surely, 2^20123671561 is an apocalyptic number.

It is an amenable number.

20123671561 is a deficient number, since it is larger than the sum of its proper divisors (4188827639).

20123671561 is a wasteful number, since it uses less digits than its factorization.

20123671561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8269.

The product of its (nonzero) digits is 15120, while the sum is 34.

The spelling of 20123671561 in words is "twenty billion, one hundred twenty-three million, six hundred seventy-one thousand, five hundred sixty-one".