20312981881 has 2 divisors, whose sum is σ = 20312981882. Its totient is φ = 20312981880.

The previous prime is 20312981831. The next prime is 20312981891. The reversal of 20312981881 is 18818921302.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17606901481 + 2706080400 = 132691^2 + 52020^2 .

It is a cyclic number.

It is not a de Polignac number, because 20312981881 - 2⁷ = 20312981753 is a prime.

It is a super-2 number, since 2×20312981881² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20312981831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10156490940 + 10156490941.

It is an arithmetic number, because the mean of its divisors is an integer number (10156490941).

Almost surely, 2^20312981881 is an apocalyptic number.

It is an amenable number.

20312981881 is a deficient number, since it is larger than the sum of its proper divisors (1).

20312981881 is an equidigital number, since it uses as much as digits as its factorization.

20312981881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 55296, while the sum is 43.

The spelling of 20312981881 in words is "twenty billion, three hundred twelve million, nine hundred eighty-one thousand, eight hundred eighty-one".