21113680657 has 2 divisors, whose sum is σ = 21113680658. Its totient is φ = 21113680656.

The previous prime is 21113680639. The next prime is 21113680697. The reversal of 21113680657 is 75608631112.

It is a happy number.

It is an a-pointer prime, because the next prime (21113680697) can be obtained adding 21113680657 to its sum of digits (40).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20867535936 + 246144721 = 144456^2 + 15689^2 .

It is a cyclic number.

It is not a de Polignac number, because 21113680657 - 2¹⁵ = 21113647889 is a prime.

It is not a weakly prime, because it can be changed into another prime (21113680697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10556840328 + 10556840329.

It is an arithmetic number, because the mean of its divisors is an integer number (10556840329).

Almost surely, 2^21113680657 is an apocalyptic number.

It is an amenable number.

21113680657 is a deficient number, since it is larger than the sum of its proper divisors (1).

21113680657 is an equidigital number, since it uses as much as digits as its factorization.

21113680657 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 60480, while the sum is 40.

The spelling of 21113680657 in words is "twenty-one billion, one hundred thirteen million, six hundred eighty thousand, six hundred fifty-seven".