21131331073 has 2 divisors, whose sum is σ = 21131331074. Its totient is φ = 21131331072.

The previous prime is 21131330963. The next prime is 21131331077. The reversal of 21131331073 is 37013313112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18723269889 + 2408061184 = 136833^2 + 49072^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21131331073 is a prime.

It is not a weakly prime, because it can be changed into another prime (21131331077) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565665536 + 10565665537.

It is an arithmetic number, because the mean of its divisors is an integer number (10565665537).

Almost surely, 2^21131331073 is an apocalyptic number.

It is an amenable number.

21131331073 is a deficient number, since it is larger than the sum of its proper divisors (1).

21131331073 is an equidigital number, since it uses as much as digits as its factorization.

21131331073 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1134, while the sum is 25.

Adding to 21131331073 its reverse (37013313112), we get a palindrome (58144644185).

The spelling of 21131331073 in words is "twenty-one billion, one hundred thirty-one million, three hundred thirty-one thousand, seventy-three".