21175151761 has 2 divisors, whose sum is σ = 21175151762. Its totient is φ = 21175151760.

The previous prime is 21175151759. The next prime is 21175151831. The reversal of 21175151761 is 16715157112.

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., 13567823361 + 7607328400 = 116481^2 + 87220^2 .

It is a cyclic number.

It is not a de Polignac number, because 21175151761 - 2¹ = 21175151759 is a prime.

It is a super-2 number, since 2×21175151761² (a number of 21 digits) contains 22 as substring.

Together with 21175151759, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21175151761.

It is not a weakly prime, because it can be changed into another prime (21175151731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10587575880 + 10587575881.

It is an arithmetic number, because the mean of its divisors is an integer number (10587575881).

Almost surely, 2^21175151761 is an apocalyptic number.

It is an amenable number.

21175151761 is a deficient number, since it is larger than the sum of its proper divisors (1).

21175151761 is an equidigital number, since it uses as much as digits as its factorization.

21175151761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14700, while the sum is 37.

The spelling of 21175151761 in words is "twenty-one billion, one hundred seventy-five million, one hundred fifty-one thousand, seven hundred sixty-one".