21345013381 has 2 divisors, whose sum is σ = 21345013382. Its totient is φ = 21345013380.

The previous prime is 21345013351. The next prime is 21345013447. The reversal of 21345013381 is 18331054312.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13921640100 + 7423373281 = 117990^2 + 86159^2 .

It is a cyclic number.

It is not a de Polignac number, because 21345013381 - 2⁷ = 21345013253 is a prime.

It is a super-2 number, since 2×21345013381² (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 (21345013331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10672506690 + 10672506691.

It is an arithmetic number, because the mean of its divisors is an integer number (10672506691).

Almost surely, 2^21345013381 is an apocalyptic number.

It is an amenable number.

21345013381 is a deficient number, since it is larger than the sum of its proper divisors (1).

21345013381 is an equidigital number, since it uses as much as digits as its factorization.

21345013381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8640, while the sum is 31.

Adding to 21345013381 its reverse (18331054312), we get a palindrome (39676067693).

The spelling of 21345013381 in words is "twenty-one billion, three hundred forty-five million, thirteen thousand, three hundred eighty-one".