21251218741 has 2 divisors, whose sum is σ = 21251218742. Its totient is φ = 21251218740.

The previous prime is 21251218733. The next prime is 21251218757. The reversal of 21251218741 is 14781215212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11610924516 + 9640294225 = 107754^2 + 98185^2 .

It is a cyclic number.

It is not a de Polignac number, because 21251218741 - 2³ = 21251218733 is a prime.

It is a super-2 number, since 2×21251218741² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21251218697 and 21251218706.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21251218841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625609370 + 10625609371.

It is an arithmetic number, because the mean of its divisors is an integer number (10625609371).

Almost surely, 2^21251218741 is an apocalyptic number.

It is an amenable number.

21251218741 is a deficient number, since it is larger than the sum of its proper divisors (1).

21251218741 is an equidigital number, since it uses as much as digits as its factorization.

21251218741 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8960, while the sum is 34.

The spelling of 21251218741 in words is "twenty-one billion, two hundred fifty-one million, two hundred eighteen thousand, seven hundred forty-one".