21100003 has 2 divisors, whose sum is σ = 21100004. Its totient is φ = 21100002.

The previous prime is 21099977. The next prime is 21100007. The reversal of 21100003 is 30000112.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21100003 is a prime.

It is not a weakly prime, because it can be changed into another prime (21100007) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550001 + 10550002.

It is an arithmetic number, because the mean of its divisors is an integer number (10550002).

Almost surely, 2^21100003 is an apocalyptic number.

21100003 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100003 is an equidigital number, since it uses as much as digits as its factorization.

21100003 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6, while the sum is 7.

The square root of 21100003 is about 4593.4739576926. The cubic root of 21100003 is about 276.3296619217.

Adding to 21100003 its reverse (30000112), we get a palindrome (51100115).

The spelling of 21100003 in words is "twenty-one million, one hundred thousand, three".