21111212010157 has 2 divisors, whose sum is σ = 21111212010158. Its totient is φ = 21111212010156.

The previous prime is 21111212010151. The next prime is 21111212010169. The reversal of 21111212010157 is 75101021211112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15368234614756 + 5742977395401 = 3920234^2 + 2396451^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21111212010157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21111212010151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555606005078 + 10555606005079.

It is an arithmetic number, because the mean of its divisors is an integer number (10555606005079).

Almost surely, 2^{21111212010157} is an apocalyptic number.

It is an amenable number.

21111212010157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111212010157 is an equidigital number, since it uses as much as digits as its factorization.

21111212010157 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 280, while the sum is 25.

Adding to 21111212010157 its reverse (75101021211112), we get a palindrome (96212233221269).

The spelling of 21111212010157 in words is "twenty-one trillion, one hundred eleven billion, two hundred twelve million, ten thousand, one hundred fifty-seven".