21717120031 has 2 divisors, whose sum is σ = 21717120032. Its totient is φ = 21717120030.

The previous prime is 21717120013. The next prime is 21717120041. The reversal of 21717120031 is 13002171712.

Together with previous prime (21717120013) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21717120031 - 2⁹ = 21717119519 is a prime.

It is a super-2 number, since 2×21717120031² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21717119978 and 21717120005.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21717120011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858560015 + 10858560016.

It is an arithmetic number, because the mean of its divisors is an integer number (10858560016).

Almost surely, 2^21717120031 is an apocalyptic number.

21717120031 is a deficient number, since it is larger than the sum of its proper divisors (1).

21717120031 is an equidigital number, since it uses as much as digits as its factorization.

21717120031 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 588, while the sum is 25.

Adding to 21717120031 its reverse (13002171712), we get a palindrome (34719291743).

The spelling of 21717120031 in words is "twenty-one billion, seven hundred seventeen million, one hundred twenty thousand, thirty-one".