21356043481 has 2 divisors, whose sum is σ = 21356043482. Its totient is φ = 21356043480.

The previous prime is 21356043413. The next prime is 21356043547. The reversal of 21356043481 is 18434065312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21058653456 + 297390025 = 145116^2 + 17245^2 .

It is a cyclic number.

It is not a de Polignac number, because 21356043481 - 2¹⁹ = 21355519193 is a prime.

It is a super-2 number, since 2×21356043481² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21356043481.

It is not a weakly prime, because it can be changed into another prime (21356043281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10678021740 + 10678021741.

It is an arithmetic number, because the mean of its divisors is an integer number (10678021741).

Almost surely, 2^21356043481 is an apocalyptic number.

It is an amenable number.

21356043481 is a deficient number, since it is larger than the sum of its proper divisors (1).

21356043481 is an equidigital number, since it uses as much as digits as its factorization.

21356043481 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 69120, while the sum is 37.

The spelling of 21356043481 in words is "twenty-one billion, three hundred fifty-six million, forty-three thousand, four hundred eighty-one".