21221099 has 2 divisors, whose sum is σ = 21221100. Its totient is φ = 21221098.

The previous prime is 21221077. The next prime is 21221113. The reversal of 21221099 is 99012212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21221099 is a prime.

It is not a weakly prime, because it can be changed into another prime (21227099) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610549 + 10610550.

It is an arithmetic number, because the mean of its divisors is an integer number (10610550).

Almost surely, 2^21221099 is an apocalyptic number.

21221099 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221099 is an equidigital number, since it uses as much as digits as its factorization.

21221099 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 21221099 is about 4606.6364084872. The cubic root of 21221099 is about 276.8572859357.

The spelling of 21221099 in words is "twenty-one million, two hundred twenty-one thousand, ninety-nine".