21398033381 has 2 divisors, whose sum is σ = 21398033382. Its totient is φ = 21398033380.

The previous prime is 21398033357. The next prime is 21398033407. The reversal of 21398033381 is 18333089312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20115748900 + 1282284481 = 141830^2 + 35809^2 .

It is a cyclic number.

It is not a de Polignac number, because 21398033381 - 2¹⁸ = 21397771237 is a prime.

It is a super-2 number, since 2×21398033381² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21398033081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10699016690 + 10699016691.

It is an arithmetic number, because the mean of its divisors is an integer number (10699016691).

Almost surely, 2^21398033381 is an apocalyptic number.

It is an amenable number.

21398033381 is a deficient number, since it is larger than the sum of its proper divisors (1).

21398033381 is an equidigital number, since it uses as much as digits as its factorization.

21398033381 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 93312, while the sum is 41.

The spelling of 21398033381 in words is "twenty-one billion, three hundred ninety-eight million, thirty-three thousand, three hundred eighty-one".