21250640381 has 2 divisors, whose sum is σ = 21250640382. Its totient is φ = 21250640380.

The previous prime is 21250640351. The next prime is 21250640417. The reversal of 21250640381 is 18304605212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12775780900 + 8474859481 = 113030^2 + 92059^2 .

It is a cyclic number.

It is not a de Polignac number, because 21250640381 - 2⁶ = 21250640317 is a prime.

It is a super-2 number, since 2×21250640381² (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 (21250640351) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625320190 + 10625320191.

It is an arithmetic number, because the mean of its divisors is an integer number (10625320191).

Almost surely, 2^21250640381 is an apocalyptic number.

It is an amenable number.

21250640381 is a deficient number, since it is larger than the sum of its proper divisors (1).

21250640381 is an equidigital number, since it uses as much as digits as its factorization.

21250640381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11520, while the sum is 32.

The spelling of 21250640381 in words is "twenty-one billion, two hundred fifty million, six hundred forty thousand, three hundred eighty-one".