21371731889 has 2 divisors, whose sum is σ = 21371731890. Its totient is φ = 21371731888.

The previous prime is 21371731877. The next prime is 21371731957. The reversal of 21371731889 is 98813717312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15598011664 + 5773720225 = 124892^2 + 75985^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21371731889 is a prime.

It is not a weakly prime, because it can be changed into another prime (21371734889) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10685865944 + 10685865945.

It is an arithmetic number, because the mean of its divisors is an integer number (10685865945).

Almost surely, 2^21371731889 is an apocalyptic number.

It is an amenable number.

21371731889 is a deficient number, since it is larger than the sum of its proper divisors (1).

21371731889 is an equidigital number, since it uses as much as digits as its factorization.

21371731889 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 508032, while the sum is 50.

The spelling of 21371731889 in words is "twenty-one billion, three hundred seventy-one million, seven hundred thirty-one thousand, eight hundred eighty-nine".