21768708361 has 2 divisors, whose sum is σ = 21768708362. Its totient is φ = 21768708360.

The previous prime is 21768708347. The next prime is 21768708371. The reversal of 21768708361 is 16380786712.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21765395961 + 3312400 = 147531^2 + 1820^2 .

It is a cyclic number.

It is not a de Polignac number, because 21768708361 - 2¹¹ = 21768706313 is a prime.

It is not a weakly prime, because it can be changed into another prime (21768708371) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10884354180 + 10884354181.

It is an arithmetic number, because the mean of its divisors is an integer number (10884354181).

Almost surely, 2^21768708361 is an apocalyptic number.

It is an amenable number.

21768708361 is a deficient number, since it is larger than the sum of its proper divisors (1).

21768708361 is an equidigital number, since it uses as much as digits as its factorization.

21768708361 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 677376, while the sum is 49.

The spelling of 21768708361 in words is "twenty-one billion, seven hundred sixty-eight million, seven hundred eight thousand, three hundred sixty-one".