21124631881 has 2 divisors, whose sum is σ = 21124631882. Its totient is φ = 21124631880.

The previous prime is 21124631831. The next prime is 21124631903. The reversal of 21124631881 is 18813642112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17145545481 + 3979086400 = 130941^2 + 63080^2 .

It is a cyclic number.

It is not a de Polignac number, because 21124631881 - 2⁷ = 21124631753 is a prime.

It is a super-2 number, since 2×21124631881² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21124631881.

It is not a weakly prime, because it can be changed into another prime (21124631831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10562315940 + 10562315941.

It is an arithmetic number, because the mean of its divisors is an integer number (10562315941).

Almost surely, 2^21124631881 is an apocalyptic number.

It is an amenable number.

21124631881 is a deficient number, since it is larger than the sum of its proper divisors (1).

21124631881 is an equidigital number, since it uses as much as digits as its factorization.

21124631881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18432, while the sum is 37.

The spelling of 21124631881 in words is "twenty-one billion, one hundred twenty-four million, six hundred thirty-one thousand, eight hundred eighty-one".