21103939 has 4 divisors (see below), whose sum is σ = 21192480. Its totient is φ = 21015400.

The previous prime is 21103937. The next prime is 21103961. The reversal of 21103939 is 93930112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21103939 - 2¹ = 21103937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21103933) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43912 + ... + 44389.

It is an arithmetic number, because the mean of its divisors is an integer number (5298120).

Almost surely, 2^21103939 is an apocalyptic number.

21103939 is a deficient number, since it is larger than the sum of its proper divisors (88541).

21103939 is an equidigital number, since it uses as much as digits as its factorization.

21103939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88540.

The product of its (nonzero) digits is 1458, while the sum is 28.

The square root of 21103939 is about 4593.9023716226. The cubic root of 21103939 is about 276.3468430555.

The spelling of 21103939 in words is "twenty-one million, one hundred three thousand, nine hundred thirty-nine".