21731417 has 2 divisors, whose sum is σ = 21731418. Its totient is φ = 21731416.

The previous prime is 21731377. The next prime is 21731419. The reversal of 21731417 is 71413712.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12845056 + 8886361 = 3584^2 + 2981^2 .

It is a cyclic number.

It is not a de Polignac number, because 21731417 - 2⁸ = 21731161 is a prime.

Together with 21731419, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21731419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10865708 + 10865709.

It is an arithmetic number, because the mean of its divisors is an integer number (10865709).

Almost surely, 2^21731417 is an apocalyptic number.

It is an amenable number.

21731417 is a deficient number, since it is larger than the sum of its proper divisors (1).

21731417 is an equidigital number, since it uses as much as digits as its factorization.

21731417 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1176, while the sum is 26.

The square root of 21731417 is about 4661.6967940869. The cubic root of 21731417 is about 279.0589881398.

The spelling of 21731417 in words is "twenty-one million, seven hundred thirty-one thousand, four hundred seventeen".