21131331077 has 2 divisors, whose sum is σ = 21131331078. Its totient is φ = 21131331076.

The previous prime is 21131331073. The next prime is 21131331113. The reversal of 21131331077 is 77013313112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21131273956 + 57121 = 145366^2 + 239^2 .

It is a cyclic number.

It is not a de Polignac number, because 21131331077 - 2² = 21131331073 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21131331073) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565665538 + 10565665539.

It is an arithmetic number, because the mean of its divisors is an integer number (10565665539).

Almost surely, 2^21131331077 is an apocalyptic number.

It is an amenable number.

21131331077 is a deficient number, since it is larger than the sum of its proper divisors (1).

21131331077 is an equidigital number, since it uses as much as digits as its factorization.

21131331077 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2646, while the sum is 29.

Adding to 21131331077 its reverse (77013313112), we get a palindrome (98144644189).

The spelling of 21131331077 in words is "twenty-one billion, one hundred thirty-one million, three hundred thirty-one thousand, seventy-seven".