21730565663 has 2 divisors, whose sum is σ = 21730565664. Its totient is φ = 21730565662.

The previous prime is 21730565657. The next prime is 21730565671. The reversal of 21730565663 is 36656503712.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21730565663 - 2⁶ = 21730565599 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21730565603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10865282831 + 10865282832.

It is an arithmetic number, because the mean of its divisors is an integer number (10865282832).

Almost surely, 2^21730565663 is an apocalyptic number.

21730565663 is a deficient number, since it is larger than the sum of its proper divisors (1).

21730565663 is an equidigital number, since it uses as much as digits as its factorization.

21730565663 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 680400, while the sum is 44.

The spelling of 21730565663 in words is "twenty-one billion, seven hundred thirty million, five hundred sixty-five thousand, six hundred sixty-three".