21502543139281 has 2 divisors, whose sum is σ = 21502543139282. Its totient is φ = 21502543139280.

The previous prime is 21502543139263. The next prime is 21502543139291. The reversal of 21502543139281 is 18293134520512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18435172704400 + 3067370434881 = 4293620^2 + 1751391^2 .

It is a cyclic number.

It is not a de Polignac number, because 21502543139281 - 2²³ = 21502534750673 is a prime.

It is a super-2 number, since 2×21502543139281² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21502543139221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10751271569640 + 10751271569641.

It is an arithmetic number, because the mean of its divisors is an integer number (10751271569641).

Almost surely, 2^{21502543139281} is an apocalyptic number.

It is an amenable number.

21502543139281 is a deficient number, since it is larger than the sum of its proper divisors (1).

21502543139281 is an equidigital number, since it uses as much as digits as its factorization.

21502543139281 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 518400, while the sum is 46.

Adding to 21502543139281 its reverse (18293134520512), we get a palindrome (39795677659793).

The spelling of 21502543139281 in words is "twenty-one trillion, five hundred two billion, five hundred forty-three million, one hundred thirty-nine thousand, two hundred eighty-one".