21173699 has 2 divisors, whose sum is σ = 21173700. Its totient is φ = 21173698.

The previous prime is 21173693. The next prime is 21173701. The reversal of 21173699 is 99637112.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21173699 - 2¹⁶ = 21108163 is a prime.

Together with 21173701, 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 (21173693) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10586849 + 10586850.

It is an arithmetic number, because the mean of its divisors is an integer number (10586850).

Almost surely, 2^21173699 is an apocalyptic number.

21173699 is a deficient number, since it is larger than the sum of its proper divisors (1).

21173699 is an equidigital number, since it uses as much as digits as its factorization.

21173699 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20412, while the sum is 38.

The square root of 21173699 is about 4601.4887808187. The cubic root of 21173699 is about 276.6510003871.

The spelling of 21173699 in words is "twenty-one million, one hundred seventy-three thousand, six hundred ninety-nine".