20128113881 has 2 divisors, whose sum is σ = 20128113882. Its totient is φ = 20128113880.

The previous prime is 20128113877. The next prime is 20128113911. The reversal of 20128113881 is 18831182102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20083424656 + 44689225 = 141716^2 + 6685^2 .

It is a cyclic number.

It is not a de Polignac number, because 20128113881 - 2² = 20128113877 is a prime.

It is a super-2 number, since 2×20128113881² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20128113871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10064056940 + 10064056941.

It is an arithmetic number, because the mean of its divisors is an integer number (10064056941).

Almost surely, 2^20128113881 is an apocalyptic number.

It is an amenable number.

20128113881 is a deficient number, since it is larger than the sum of its proper divisors (1).

20128113881 is an equidigital number, since it uses as much as digits as its factorization.

20128113881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6144, while the sum is 35.

Adding to 20128113881 its reverse (18831182102), we get a palindrome (38959295983).

The spelling of 20128113881 in words is "twenty billion, one hundred twenty-eight million, one hundred thirteen thousand, eight hundred eighty-one".