21517783927 has 2 divisors, whose sum is σ = 21517783928. Its totient is φ = 21517783926.

The previous prime is 21517783913. The next prime is 21517783943. The reversal of 21517783927 is 72938771512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21517783927 - 2¹⁹ = 21517259639 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21517783907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10758891963 + 10758891964.

It is an arithmetic number, because the mean of its divisors is an integer number (10758891964).

Almost surely, 2^21517783927 is an apocalyptic number.

21517783927 is a deficient number, since it is larger than the sum of its proper divisors (1).

21517783927 is an equidigital number, since it uses as much as digits as its factorization.

21517783927 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1481760, while the sum is 52.

The spelling of 21517783927 in words is "twenty-one billion, five hundred seventeen million, seven hundred eighty-three thousand, nine hundred twenty-seven".