21673517 has 2 divisors, whose sum is σ = 21673518. Its totient is φ = 21673516.

The previous prime is 21673511. The next prime is 21673523. The reversal of 21673517 is 71537612.

It is a balanced prime because it is at equal distance from previous prime (21673511) and next prime (21673523).

It can be written as a sum of positive squares in only one way, i.e., 20376196 + 1297321 = 4514^2 + 1139^2 .

It is a cyclic number.

It is not a de Polignac number, because 21673517 - 2⁸ = 21673261 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 (21673511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10836758 + 10836759.

It is an arithmetic number, because the mean of its divisors is an integer number (10836759).

Almost surely, 2^21673517 is an apocalyptic number.

It is an amenable number.

21673517 is a deficient number, since it is larger than the sum of its proper divisors (1).

21673517 is an equidigital number, since it uses as much as digits as its factorization.

21673517 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8820, while the sum is 32.

The square root of 21673517 is about 4655.4824669415. The cubic root of 21673517 is about 278.8109311995.

The spelling of 21673517 in words is "twenty-one million, six hundred seventy-three thousand, five hundred seventeen".