21240235255177 has 2 divisors, whose sum is σ = 21240235255178. Its totient is φ = 21240235255176.

The previous prime is 21240235255123. The next prime is 21240235255223. The reversal of 21240235255177 is 77155253204212.

It is an a-pointer prime, because the next prime (21240235255223) can be obtained adding 21240235255177 to its sum of digits (46).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19783316248336 + 1456919006841 = 4447844^2 + 1207029^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21240235255177 is a prime.

It is a super-2 number, since 2×21240235255177² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21240235255277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10620117627588 + 10620117627589.

It is an arithmetic number, because the mean of its divisors is an integer number (10620117627589).

Almost surely, 2^{21240235255177} is an apocalyptic number.

It is an amenable number.

21240235255177 is a deficient number, since it is larger than the sum of its proper divisors (1).

21240235255177 is an equidigital number, since it uses as much as digits as its factorization.

21240235255177 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1176000, while the sum is 46.

Adding to 21240235255177 its reverse (77155253204212), we get a palindrome (98395488459389).

The spelling of 21240235255177 in words is "twenty-one trillion, two hundred forty billion, two hundred thirty-five million, two hundred fifty-five thousand, one hundred seventy-seven".