21421411381 has 2 divisors, whose sum is σ = 21421411382. Its totient is φ = 21421411380.

The previous prime is 21421411337. The next prime is 21421411423. The reversal of 21421411381 is 18311412412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14769540900 + 6651870481 = 121530^2 + 81559^2 .

It is a cyclic number.

It is not a de Polignac number, because 21421411381 - 2⁹ = 21421410869 is a prime.

It is a super-2 number, since 2×21421411381² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21421411681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710705690 + 10710705691.

It is an arithmetic number, because the mean of its divisors is an integer number (10710705691).

Almost surely, 2^21421411381 is an apocalyptic number.

It is an amenable number.

21421411381 is a deficient number, since it is larger than the sum of its proper divisors (1).

21421411381 is an equidigital number, since it uses as much as digits as its factorization.

21421411381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1536, while the sum is 28.

Adding to 21421411381 its reverse (18311412412), we get a palindrome (39732823793).

The spelling of 21421411381 in words is "twenty-one billion, four hundred twenty-one million, four hundred eleven thousand, three hundred eighty-one".