21200120212157 has 2 divisors, whose sum is σ = 21200120212158. Its totient is φ = 21200120212156.

The previous prime is 21200120212129. The next prime is 21200120212223. The reversal of 21200120212157 is 75121202100212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12185168007076 + 9014952205081 = 3490726^2 + 3002491^2 .

It is a cyclic number.

It is not a de Polignac number, because 21200120212157 - 2²⁴ = 21200103434941 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21200120214157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600060106078 + 10600060106079.

It is an arithmetic number, because the mean of its divisors is an integer number (10600060106079).

Almost surely, 2^{21200120212157} is an apocalyptic number.

It is an amenable number.

21200120212157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21200120212157 is an equidigital number, since it uses as much as digits as its factorization.

21200120212157 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1120, while the sum is 26.

Adding to 21200120212157 its reverse (75121202100212), we get a palindrome (96321322312369).

The spelling of 21200120212157 in words is "twenty-one trillion, two hundred billion, one hundred twenty million, two hundred twelve thousand, one hundred fifty-seven".