21100939 has 2 divisors, whose sum is σ = 21100940. Its totient is φ = 21100938.

The previous prime is 21100931. The next prime is 21100949. The reversal of 21100939 is 93900112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21100939 - 2³ = 21100931 is a prime.

It is not a weakly prime, because it can be changed into another prime (21100931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550469 + 10550470.

It is an arithmetic number, because the mean of its divisors is an integer number (10550470).

Almost surely, 2^21100939 is an apocalyptic number.

21100939 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100939 is an equidigital number, since it uses as much as digits as its factorization.

21100939 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 486, while the sum is 25.

The square root of 21100939 is about 4593.5758402360. The cubic root of 21100939 is about 276.3337478727. Note that the first 3 decimals are identical.

The spelling of 21100939 in words is "twenty-one million, one hundred thousand, nine hundred thirty-nine".