21716533 has 2 divisors, whose sum is σ = 21716534. Its totient is φ = 21716532.

The previous prime is 21716507. The next prime is 21716567. The reversal of 21716533 is 33561712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12517444 + 9199089 = 3538^2 + 3033^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21716533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21716503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858266 + 10858267.

It is an arithmetic number, because the mean of its divisors is an integer number (10858267).

Almost surely, 2^21716533 is an apocalyptic number.

It is an amenable number.

21716533 is a deficient number, since it is larger than the sum of its proper divisors (1).

21716533 is an equidigital number, since it uses as much as digits as its factorization.

21716533 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3780, while the sum is 28.

The square root of 21716533 is about 4660.1001062209. The cubic root of 21716533 is about 278.9952637694.

The spelling of 21716533 in words is "twenty-one million, seven hundred sixteen thousand, five hundred thirty-three".