21155211314453 has 2 divisors, whose sum is σ = 21155211314454. Its totient is φ = 21155211314452.

The previous prime is 21155211314449. The next prime is 21155211314459. The reversal of 21155211314453 is 35441311255112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15574688604484 + 5580522709969 = 3946478^2 + 2362313^2 .

It is a cyclic number.

It is not a de Polignac number, because 21155211314453 - 2² = 21155211314449 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21155211314459) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10577605657226 + 10577605657227.

It is an arithmetic number, because the mean of its divisors is an integer number (10577605657227).

Almost surely, 2^{21155211314453} is an apocalyptic number.

It is an amenable number.

21155211314453 is a deficient number, since it is larger than the sum of its proper divisors (1).

21155211314453 is an equidigital number, since it uses as much as digits as its factorization.

21155211314453 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72000, while the sum is 38.

Adding to 21155211314453 its reverse (35441311255112), we get a palindrome (56596522569565).

The spelling of 21155211314453 in words is "twenty-one trillion, one hundred fifty-five billion, two hundred eleven million, three hundred fourteen thousand, four hundred fifty-three".