21910717 has 2 divisors, whose sum is σ = 21910718. Its totient is φ = 21910716.

The previous prime is 21910703. The next prime is 21910727. The reversal of 21910717 is 71701912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21659716 + 251001 = 4654^2 + 501^2 .

It is a cyclic number.

It is not a de Polignac number, because 21910717 - 2¹⁹ = 21386429 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 (21910727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10955358 + 10955359.

It is an arithmetic number, because the mean of its divisors is an integer number (10955359).

Almost surely, 2^21910717 is an apocalyptic number.

It is an amenable number.

21910717 is a deficient number, since it is larger than the sum of its proper divisors (1).

21910717 is an equidigital number, since it uses as much as digits as its factorization.

21910717 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 882, while the sum is 28.

The square root of 21910717 is about 4680.8884840380. Note that the first 3 decimals coincide. The cubic root of 21910717 is about 279.8243668960.

The spelling of 21910717 in words is "twenty-one million, nine hundred ten thousand, seven hundred seventeen".