20872981261 has 4 divisors (see below), whose sum is σ = 22770525024. Its totient is φ = 18975437500.

The previous prime is 20872981243. The next prime is 20872981277. The reversal of 20872981261 is 16218927802.

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 20872981261 - 2⁷ = 20872981133 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 (20872981291) 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, 948771865 + ... + 948771886.

It is an arithmetic number, because the mean of its divisors is an integer number (5692631256).

Almost surely, 2^20872981261 is an apocalyptic number.

It is an amenable number.

20872981261 is a deficient number, since it is larger than the sum of its proper divisors (1897543763).

20872981261 is a wasteful number, since it uses less digits than its factorization.

20872981261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1897543762.

The product of its (nonzero) digits is 193536, while the sum is 46.

The spelling of 20872981261 in words is "twenty billion, eight hundred seventy-two million, nine hundred eighty-one thousand, two hundred sixty-one".