21716567 has 2 divisors, whose sum is σ = 21716568. Its totient is φ = 21716566.

The previous prime is 21716533. The next prime is 21716573. The reversal of 21716567 is 76561712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21716567 - 2⁶ = 21716503 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21716507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858283 + 10858284.

It is an arithmetic number, because the mean of its divisors is an integer number (10858284).

Almost surely, 2^21716567 is an apocalyptic number.

21716567 is a deficient number, since it is larger than the sum of its proper divisors (1).

21716567 is an equidigital number, since it uses as much as digits as its factorization.

21716567 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17640, while the sum is 35.

The square root of 21716567 is about 4660.1037542098. The cubic root of 21716567 is about 278.9954093702.

The spelling of 21716567 in words is "twenty-one million, seven hundred sixteen thousand, five hundred sixty-seven".