21217277 has 2 divisors, whose sum is σ = 21217278. Its totient is φ = 21217276.

The previous prime is 21217271. The next prime is 21217289. The reversal of 21217277 is 77271212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12859396 + 8357881 = 3586^2 + 2891^2 .

It is a cyclic number.

It is not a de Polignac number, because 21217277 - 2¹⁰ = 21216253 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 (21217271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10608638 + 10608639.

It is an arithmetic number, because the mean of its divisors is an integer number (10608639).

Almost surely, 2^21217277 is an apocalyptic number.

It is an amenable number.

21217277 is a deficient number, since it is larger than the sum of its proper divisors (1).

21217277 is an equidigital number, since it uses as much as digits as its factorization.

21217277 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2744, while the sum is 29.

The square root of 21217277 is about 4606.2215535078. The cubic root of 21217277 is about 276.8406639238.

Adding to 21217277 its reverse (77271212), we get a palindrome (98488489).

The spelling of 21217277 in words is "twenty-one million, two hundred seventeen thousand, two hundred seventy-seven".