21515004211361 has 2 divisors, whose sum is σ = 21515004211362. Its totient is φ = 21515004211360.

The previous prime is 21515004211277. The next prime is 21515004211423. The reversal of 21515004211361 is 16311240051512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20011584911761 + 1503419299600 = 4473431^2 + 1226140^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21515004211361 is a prime.

It is a super-2 number, since 2×21515004211361² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21515004213361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10757502105680 + 10757502105681.

It is an arithmetic number, because the mean of its divisors is an integer number (10757502105681).

Almost surely, 2^{21515004211361} is an apocalyptic number.

It is an amenable number.

21515004211361 is a deficient number, since it is larger than the sum of its proper divisors (1).

21515004211361 is an equidigital number, since it uses as much as digits as its factorization.

21515004211361 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7200, while the sum is 32.

Adding to 21515004211361 its reverse (16311240051512), we get a palindrome (37826244262873).

The spelling of 21515004211361 in words is "twenty-one trillion, five hundred fifteen billion, four million, two hundred eleven thousand, three hundred sixty-one".