21405365453 has 2 divisors, whose sum is σ = 21405365454. Its totient is φ = 21405365452.

The previous prime is 21405365417. The next prime is 21405365483. The reversal of 21405365453 is 35456350412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15494523529 + 5910841924 = 124477^2 + 76882^2 .

It is a cyclic number.

It is not a de Polignac number, because 21405365453 - 2¹⁰ = 21405364429 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21405365483) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10702682726 + 10702682727.

It is an arithmetic number, because the mean of its divisors is an integer number (10702682727).

Almost surely, 2^21405365453 is an apocalyptic number.

It is an amenable number.

21405365453 is a deficient number, since it is larger than the sum of its proper divisors (1).

21405365453 is an equidigital number, since it uses as much as digits as its factorization.

21405365453 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216000, while the sum is 38.

The spelling of 21405365453 in words is "twenty-one billion, four hundred five million, three hundred sixty-five thousand, four hundred fifty-three".