21101207 has 2 divisors, whose sum is σ = 21101208. Its totient is φ = 21101206.

The previous prime is 21101123. The next prime is 21101209. The reversal of 21101207 is 70210112.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21101207 is a prime.

Together with 21101209, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21101191 and 21101200.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21101209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550603 + 10550604.

It is an arithmetic number, because the mean of its divisors is an integer number (10550604).

Almost surely, 2^21101207 is an apocalyptic number.

21101207 is a deficient number, since it is larger than the sum of its proper divisors (1).

21101207 is an equidigital number, since it uses as much as digits as its factorization.

21101207 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 28, while the sum is 14.

The square root of 21101207 is about 4593.6050113174. The cubic root of 21101207 is about 276.3349177595.

Adding to 21101207 its reverse (70210112), we get a palindrome (91311319).

The spelling of 21101207 in words is "twenty-one million, one hundred one thousand, two hundred seven".