21020121112157 has 2 divisors, whose sum is σ = 21020121112158. Its totient is φ = 21020121112156.

The previous prime is 21020121112091. The next prime is 21020121112217. The reversal of 21020121112157 is 75121112102012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13202314983001 + 7817806129156 = 3633499^2 + 2796034^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020121112157 - 2⁸ = 21020121111901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21020121612157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510060556078 + 10510060556079.

It is an arithmetic number, because the mean of its divisors is an integer number (10510060556079).

Almost surely, 2^{21020121112157} is an apocalyptic number.

It is an amenable number.

21020121112157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020121112157 is an equidigital number, since it uses as much as digits as its factorization.

21020121112157 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 560, while the sum is 26.

Adding to 21020121112157 its reverse (75121112102012), we get a palindrome (96141233214169).

The spelling of 21020121112157 in words is "twenty-one trillion, twenty billion, one hundred twenty-one million, one hundred twelve thousand, one hundred fifty-seven".