21240098177981 has 6 divisors (see below), whose sum is σ = 21829669933050. Its totient is φ = 20666041469136.

The previous prime is 21240098177959. The next prime is 21240098178001. The reversal of 21240098177981 is 18977189004212.

It can be written as a sum of positive squares in 3 ways, for example, as 15093496951225 + 6146601226756 = 3885035^2 + 2479234^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21240098177981 is a prime.

It is a super-2 number, since 2×21240098177981² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21240098177981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21240098179981) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7757521706 + ... + 7757524443.

It is an arithmetic number, because the mean of its divisors is an integer number (3638278322175).

Almost surely, 2^{21240098177981} is an apocalyptic number.

It is an amenable number.

21240098177981 is a deficient number, since it is larger than the sum of its proper divisors (589571755069).

21240098177981 is an equidigital number, since it uses as much as digits as its factorization.

21240098177981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15515046223 (or 15515046186 counting only the distinct ones).

The product of its (nonzero) digits is 4064256, while the sum is 59.

The spelling of 21240098177981 in words is "twenty-one trillion, two hundred forty billion, ninety-eight million, one hundred seventy-seven thousand, nine hundred eighty-one".