21354727216397 has 2 divisors, whose sum is σ = 21354727216398. Its totient is φ = 21354727216396.

The previous prime is 21354727216379. The next prime is 21354727216519. The reversal of 21354727216397 is 79361272745312.

Together with previous prime (21354727216379) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17601960129961 + 3752767086436 = 4195469^2 + 1937206^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21354727216397 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21354727218397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10677363608198 + 10677363608199.

It is an arithmetic number, because the mean of its divisors is an integer number (10677363608199).

Almost surely, 2^{21354727216397} is an apocalyptic number.

It is an amenable number.

21354727216397 is a deficient number, since it is larger than the sum of its proper divisors (1).

21354727216397 is an equidigital number, since it uses as much as digits as its factorization.

21354727216397 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26671680, while the sum is 59.

The spelling of 21354727216397 in words is "twenty-one trillion, three hundred fifty-four billion, seven hundred twenty-seven million, two hundred sixteen thousand, three hundred ninety-seven".