21085567 has 2 divisors, whose sum is σ = 21085568. Its totient is φ = 21085566.

The previous prime is 21085543. The next prime is 21085577. The reversal of 21085567 is 76558012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21085567 is a prime.

It is a super-2 number, since 2×21085567² = 889202271422978, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21085577) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10542783 + 10542784.

It is an arithmetic number, because the mean of its divisors is an integer number (10542784).

Almost surely, 2^21085567 is an apocalyptic number.

21085567 is a deficient number, since it is larger than the sum of its proper divisors (1).

21085567 is an equidigital number, since it uses as much as digits as its factorization.

21085567 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16800, while the sum is 34.

The square root of 21085567 is about 4591.9023291007. The cubic root of 21085567 is about 276.2666286749.

The spelling of 21085567 in words is "twenty-one million, eighty-five thousand, five hundred sixty-seven".