21837389081 has 2 divisors, whose sum is σ = 21837389082. Its totient is φ = 21837389080.

The previous prime is 21837389039. The next prime is 21837389129. The reversal of 21837389081 is 18098373812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13523596681 + 8313792400 = 116291^2 + 91180^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21837389081 is a prime.

It is a super-2 number, since 2×21837389081² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21837389281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10918694540 + 10918694541.

It is an arithmetic number, because the mean of its divisors is an integer number (10918694541).

Almost surely, 2^21837389081 is an apocalyptic number.

It is an amenable number.

21837389081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21837389081 is an equidigital number, since it uses as much as digits as its factorization.

21837389081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 580608, while the sum is 50.

The spelling of 21837389081 in words is "twenty-one billion, eight hundred thirty-seven million, three hundred eighty-nine thousand, eighty-one".