21489363881 has 2 divisors, whose sum is σ = 21489363882. Its totient is φ = 21489363880.

The previous prime is 21489363823. The next prime is 21489363911. The reversal of 21489363881 is 18836398412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21478368025 + 10995856 = 146555^2 + 3316^2 .

It is a cyclic number.

It is not a de Polignac number, because 21489363881 - 2⁶ = 21489363817 is a prime.

It is a super-2 number, since 2×21489363881² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21489363811) 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 as a sum of consecutive naturals, namely, 10744681940 + 10744681941.

It is an arithmetic number, because the mean of its divisors is an integer number (10744681941).

Almost surely, 2^21489363881 is an apocalyptic number.

It is an amenable number.

21489363881 is a deficient number, since it is larger than the sum of its proper divisors (1).

21489363881 is an equidigital number, since it uses as much as digits as its factorization.

21489363881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1990656, while the sum is 53.

The spelling of 21489363881 in words is "twenty-one billion, four hundred eighty-nine million, three hundred sixty-three thousand, eight hundred eighty-one".