21100207 has 2 divisors, whose sum is σ = 21100208. Its totient is φ = 21100206.

The previous prime is 21100193. The next prime is 21100217. The reversal of 21100207 is 70200112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21100207 - 2¹⁵ = 21067439 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21100217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550103 + 10550104.

It is an arithmetic number, because the mean of its divisors is an integer number (10550104).

Almost surely, 2^21100207 is an apocalyptic number.

21100207 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100207 is an equidigital number, since it uses as much as digits as its factorization.

21100207 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28, while the sum is 13.

The square root of 21100207 is about 4593.4961630549. The cubic root of 21100207 is about 276.3305524597.

Adding to 21100207 its reverse (70200112), we get a palindrome (91300319).

The spelling of 21100207 in words is "twenty-one million, one hundred thousand, two hundred seven".