21255205450663 has 2 divisors, whose sum is σ = 21255205450664. Its totient is φ = 21255205450662.

The previous prime is 21255205450639. The next prime is 21255205450693. The reversal of 21255205450663 is 36605450255212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21255205450663 - 2¹⁷ = 21255205319591 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21255205450693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10627602725331 + 10627602725332.

It is an arithmetic number, because the mean of its divisors is an integer number (10627602725332).

Almost surely, 2^{21255205450663} is an apocalyptic number.

21255205450663 is a deficient number, since it is larger than the sum of its proper divisors (1).

21255205450663 is an equidigital number, since it uses as much as digits as its factorization.

21255205450663 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160000, while the sum is 46.

The spelling of 21255205450663 in words is "twenty-one trillion, two hundred fifty-five billion, two hundred five million, four hundred fifty thousand, six hundred sixty-three".