20121989977 has 2 divisors, whose sum is σ = 20121989978. Its totient is φ = 20121989976.

The previous prime is 20121989813. The next prime is 20121989989. The reversal of 20121989977 is 77998912102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17103146841 + 3018843136 = 130779^2 + 54944^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20121989977 is a prime.

It is not a weakly prime, because it can be changed into another prime (20121989177) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10060994988 + 10060994989.

It is an arithmetic number, because the mean of its divisors is an integer number (10060994989).

Almost surely, 2^20121989977 is an apocalyptic number.

It is an amenable number.

20121989977 is a deficient number, since it is larger than the sum of its proper divisors (1).

20121989977 is an equidigital number, since it uses as much as digits as its factorization.

20121989977 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1143072, while the sum is 55.

The spelling of 20121989977 in words is "twenty billion, one hundred twenty-one million, nine hundred eighty-nine thousand, nine hundred seventy-seven".