21202118137 has 2 divisors, whose sum is σ = 21202118138. Its totient is φ = 21202118136.

The previous prime is 21202118117. The next prime is 21202118141. The reversal of 21202118137 is 73181120212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19558302201 + 1643815936 = 139851^2 + 40544^2 .

It is a cyclic number.

It is not a de Polignac number, because 21202118137 - 2¹⁵ = 21202085369 is a prime.

It is not a weakly prime, because it can be changed into another prime (21202118117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601059068 + 10601059069.

It is an arithmetic number, because the mean of its divisors is an integer number (10601059069).

Almost surely, 2^21202118137 is an apocalyptic number.

It is an amenable number.

21202118137 is a deficient number, since it is larger than the sum of its proper divisors (1).

21202118137 is an equidigital number, since it uses as much as digits as its factorization.

21202118137 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1344, while the sum is 28.

Adding to 21202118137 its reverse (73181120212), we get a palindrome (94383238349).

The spelling of 21202118137 in words is "twenty-one billion, two hundred two million, one hundred eighteen thousand, one hundred thirty-seven".