21481547363813 has 4 divisors (see below), whose sum is σ = 21722913064620. Its totient is φ = 21240181663008.

The previous prime is 21481547363779. The next prime is 21481547363851. The reversal of 21481547363813 is 31836374518412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1882005347044 + 19599542016769 = 1371862^2 + 4427137^2 .

It is a cyclic number.

It is not a de Polignac number, because 21481547363813 - 2¹⁸ = 21481547101669 is a prime.

It is a super-2 number, since 2×21481547363813² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21481547363113) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 120682850270 + ... + 120682850447.

It is an arithmetic number, because the mean of its divisors is an integer number (5430728266155).

Almost surely, 2^{21481547363813} is an apocalyptic number.

It is an amenable number.

21481547363813 is a deficient number, since it is larger than the sum of its proper divisors (241365700807).

21481547363813 is an equidigital number, since it uses as much as digits as its factorization.

21481547363813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241365700806.

The product of its digits is 11612160, while the sum is 56.

The spelling of 21481547363813 in words is "twenty-one trillion, four hundred eighty-one billion, five hundred forty-seven million, three hundred sixty-three thousand, eight hundred thirteen".