21103999 has 8 divisors (see below), whose sum is σ = 24368288. Its totient is φ = 17902080.

The previous prime is 21103961. The next prime is 21104011. The reversal of 21103999 is 99930112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21103999 - 2¹⁹ = 20579711 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14862 + ... + 16219.

It is an arithmetic number, because the mean of its divisors is an integer number (3046036).

Almost surely, 2^21103999 is an apocalyptic number.

21103999 is a deficient number, since it is larger than the sum of its proper divisors (3264289).

21103999 is an equidigital number, since it uses as much as digits as its factorization.

21103999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31185.

The product of its (nonzero) digits is 4374, while the sum is 34.

The square root of 21103999 is about 4593.9089020136. The cubic root of 21103999 is about 276.3471049465.

The spelling of 21103999 in words is "twenty-one million, one hundred three thousand, nine hundred ninety-nine".