21337281761 has 2 divisors, whose sum is σ = 21337281762. Its totient is φ = 21337281760.

The previous prime is 21337281743. The next prime is 21337281781. The reversal of 21337281761 is 16718273312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18972307600 + 2364974161 = 137740^2 + 48631^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21337281761 is a prime.

It is a super-2 number, since 2×21337281761² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21337281781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10668640880 + 10668640881.

It is an arithmetic number, because the mean of its divisors is an integer number (10668640881).

Almost surely, 2^21337281761 is an apocalyptic number.

It is an amenable number.

21337281761 is a deficient number, since it is larger than the sum of its proper divisors (1).

21337281761 is an equidigital number, since it uses as much as digits as its factorization.

21337281761 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 84672, while the sum is 41.

The spelling of 21337281761 in words is "twenty-one billion, three hundred thirty-seven million, two hundred eighty-one thousand, seven hundred sixty-one".