20813971881 has 8 divisors (see below), whose sum is σ = 27764377344. Its totient is φ = 13869773840.

The previous prime is 20813971847. The next prime is 20813971889. The reversal of 20813971881 is 18817931802.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20813971881 - 2²¹ = 20811874729 is a prime.

It is a super-2 number, since 2×20813971881² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20813971881.

It is not an unprimeable number, because it can be changed into a prime (20813971889) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1544025 + ... + 1557446.

It is an arithmetic number, because the mean of its divisors is an integer number (3470547168).

Almost surely, 2^20813971881 is an apocalyptic number.

It is an amenable number.

20813971881 is a deficient number, since it is larger than the sum of its proper divisors (6950405463).

20813971881 is a wasteful number, since it uses less digits than its factorization.

20813971881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3103711.

The product of its (nonzero) digits is 193536, while the sum is 48.

The spelling of 20813971881 in words is "twenty billion, eight hundred thirteen million, nine hundred seventy-one thousand, eight hundred eighty-one".