21117306631 has 2 divisors, whose sum is σ = 21117306632. Its totient is φ = 21117306630.

The previous prime is 21117306583. The next prime is 21117306643. The reversal of 21117306631 is 13660371112.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21117306631 is a prime.

It is a super-2 number, since 2×21117306631² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21117306593 and 21117306602.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21117301631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10558653315 + 10558653316.

It is an arithmetic number, because the mean of its divisors is an integer number (10558653316).

Almost surely, 2^21117306631 is an apocalyptic number.

21117306631 is a deficient number, since it is larger than the sum of its proper divisors (1).

21117306631 is an equidigital number, since it uses as much as digits as its factorization.

21117306631 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4536, while the sum is 31.

Adding to 21117306631 its reverse (13660371112), we get a palindrome (34777677743).

The spelling of 21117306631 in words is "twenty-one billion, one hundred seventeen million, three hundred six thousand, six hundred thirty-one".