21861083381 has 4 divisors (see below), whose sum is σ = 21878587500. Its totient is φ = 21843579264.

The previous prime is 21861083357. The next prime is 21861083407. The reversal of 21861083381 is 18338016812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16080522481 + 5780560900 = 126809^2 + 76030^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21861083381 is a prime.

It is a super-2 number, since 2×21861083381² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21861053381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8750186 + ... + 8752683.

It is an arithmetic number, because the mean of its divisors is an integer number (5469646875).

Almost surely, 2^21861083381 is an apocalyptic number.

It is an amenable number.

21861083381 is a deficient number, since it is larger than the sum of its proper divisors (17504119).

21861083381 is a wasteful number, since it uses less digits than its factorization.

21861083381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17504118.

The product of its (nonzero) digits is 55296, while the sum is 41.

The spelling of 21861083381 in words is "twenty-one billion, eight hundred sixty-one million, eighty-three thousand, three hundred eighty-one".