20989042181 has 4 divisors (see below), whose sum is σ = 20989397664. Its totient is φ = 20988686700.

The previous prime is 20989042169. The next prime is 20989042183. The reversal of 20989042181 is 18124098902.

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 a de Polignac number, because none of the positive numbers 2^k-20989042181 is a prime.

It is a super-2 number, since 2×20989042181² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20989042183) 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, 65585 + ... + 215126.

It is an arithmetic number, because the mean of its divisors is an integer number (5247349416).

Almost surely, 2^20989042181 is an apocalyptic number.

It is an amenable number.

20989042181 is a deficient number, since it is larger than the sum of its proper divisors (355483).

20989042181 is an equidigital number, since it uses as much as digits as its factorization.

20989042181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355482.

The product of its (nonzero) digits is 82944, while the sum is 44.

The spelling of 20989042181 in words is "twenty billion, nine hundred eighty-nine million, forty-two thousand, one hundred eighty-one".