21500520221287 has 2 divisors, whose sum is σ = 21500520221288. Its totient is φ = 21500520221286.

The previous prime is 21500520221273. The next prime is 21500520221357. The reversal of 21500520221287 is 78212202500512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21500520221287 - 2¹¹ = 21500520219239 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21500520231287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10750260110643 + 10750260110644.

It is an arithmetic number, because the mean of its divisors is an integer number (10750260110644).

Almost surely, 2^{21500520221287} is an apocalyptic number.

21500520221287 is a deficient number, since it is larger than the sum of its proper divisors (1).

21500520221287 is an equidigital number, since it uses as much as digits as its factorization.

21500520221287 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 44800, while the sum is 37.

Adding to 21500520221287 its reverse (78212202500512), we get a palindrome (99712722721799).

The spelling of 21500520221287 in words is "twenty-one trillion, five hundred billion, five hundred twenty million, two hundred twenty-one thousand, two hundred eighty-seven".