21767608742881 has 2 divisors, whose sum is σ = 21767608742882. Its totient is φ = 21767608742880.

The previous prime is 21767608742879. The next prime is 21767608742963. The reversal of 21767608742881 is 18824780676712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21649850643600 + 117758099281 = 4652940^2 + 343159^2 .

It is a cyclic number.

It is not a de Polignac number, because 21767608742881 - 2¹ = 21767608742879 is a prime.

It is a super-2 number, since 2×21767608742881² (a number of 27 digits) contains 22 as substring.

Together with 21767608742879, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21767608742681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10883804371440 + 10883804371441.

It is an arithmetic number, because the mean of its divisors is an integer number (10883804371441).

Almost surely, 2^{21767608742881} is an apocalyptic number.

It is an amenable number.

21767608742881 is a deficient number, since it is larger than the sum of its proper divisors (1).

21767608742881 is an equidigital number, since it uses as much as digits as its factorization.

21767608742881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 101154816, while the sum is 67.

The spelling of 21767608742881 in words is "twenty-one trillion, seven hundred sixty-seven billion, six hundred eight million, seven hundred forty-two thousand, eight hundred eighty-one".