21555368158507 has 2 divisors, whose sum is σ = 21555368158508. Its totient is φ = 21555368158506.

The previous prime is 21555368158483. The next prime is 21555368158529. The reversal of 21555368158507 is 70585186355512.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21555368158507 is a prime.

It is not a weakly prime, because it can be changed into another prime (21555368158547) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10777684079253 + 10777684079254.

It is an arithmetic number, because the mean of its divisors is an integer number (10777684079254).

Almost surely, 2^{21555368158507} is an apocalyptic number.

21555368158507 is a deficient number, since it is larger than the sum of its proper divisors (1).

21555368158507 is an equidigital number, since it uses as much as digits as its factorization.

21555368158507 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 50400000, while the sum is 61.

The spelling of 21555368158507 in words is "twenty-one trillion, five hundred fifty-five billion, three hundred sixty-eight million, one hundred fifty-eight thousand, five hundred seven".