21505766467 has 2 divisors, whose sum is σ = 21505766468. Its totient is φ = 21505766466.

The previous prime is 21505766461. The next prime is 21505766519. The reversal of 21505766467 is 76466750512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21505766467 - 2³ = 21505766459 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21505766467.

It is not a weakly prime, because it can be changed into another prime (21505766461) 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, 10752883233 + 10752883234.

It is an arithmetic number, because the mean of its divisors is an integer number (10752883234).

Almost surely, 2^21505766467 is an apocalyptic number.

21505766467 is a deficient number, since it is larger than the sum of its proper divisors (1).

21505766467 is an equidigital number, since it uses as much as digits as its factorization.

21505766467 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2116800, while the sum is 49.

The spelling of 21505766467 in words is "twenty-one billion, five hundred five million, seven hundred sixty-six thousand, four hundred sixty-seven".