21121153134637 has 2 divisors, whose sum is σ = 21121153134638. Its totient is φ = 21121153134636.

The previous prime is 21121153134611. The next prime is 21121153134643. The reversal of 21121153134637 is 73643135112112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20033448063876 + 1087705070761 = 4475874^2 + 1042931^2 .

It is a cyclic number.

It is not a de Polignac number, because 21121153134637 - 2⁷ = 21121153134509 is a prime.

It is a super-2 number, since 2×21121153134637² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21121153134637.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21121153134677) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560576567318 + 10560576567319.

It is an arithmetic number, because the mean of its divisors is an integer number (10560576567319).

Almost surely, 2^{21121153134637} is an apocalyptic number.

It is an amenable number.

21121153134637 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121153134637 is an equidigital number, since it uses as much as digits as its factorization.

21121153134637 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 40.

Adding to 21121153134637 its reverse (73643135112112), we get a palindrome (94764288246749).

The spelling of 21121153134637 in words is "twenty-one trillion, one hundred twenty-one billion, one hundred fifty-three million, one hundred thirty-four thousand, six hundred thirty-seven".