21064085381 has 2 divisors, whose sum is σ = 21064085382. Its totient is φ = 21064085380.

The previous prime is 21064085353. The next prime is 21064085407. The reversal of 21064085381 is 18358046012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20901930625 + 162154756 = 144575^2 + 12734^2 .

It is a cyclic number.

It is not a de Polignac number, because 21064085381 - 2¹⁸ = 21063823237 is a prime.

It is a super-2 number, since 2×21064085381² (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 (21064085321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10532042690 + 10532042691.

It is an arithmetic number, because the mean of its divisors is an integer number (10532042691).

Almost surely, 2^21064085381 is an apocalyptic number.

It is an amenable number.

21064085381 is a deficient number, since it is larger than the sum of its proper divisors (1).

21064085381 is an equidigital number, since it uses as much as digits as its factorization.

21064085381 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46080, while the sum is 38.

The spelling of 21064085381 in words is "twenty-one billion, sixty-four million, eighty-five thousand, three hundred eighty-one".