21390303 has 8 divisors (see below), whose sum is σ = 31113216. Its totient is φ = 12963800.

The previous prime is 21390289. The next prime is 21390337. The reversal of 21390303 is 30309312.

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

It is a cyclic number.

It is not a de Polignac number, because 21390303 - 2⁴ = 21390287 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21390303.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21390503) 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, 324063 + ... + 324128.

It is an arithmetic number, because the mean of its divisors is an integer number (3889152).

Almost surely, 2^21390303 is an apocalyptic number.

21390303 is a deficient number, since it is larger than the sum of its proper divisors (9722913).

21390303 is a wasteful number, since it uses less digits than its factorization.

21390303 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 648205.

The product of its (nonzero) digits is 486, while the sum is 21.

The square root of 21390303 is about 4624.9651890582. The cubic root of 21390303 is about 277.5911688108.

Adding to 21390303 its reverse (30309312), we get a palindrome (51699615).

The spelling of 21390303 in words is "twenty-one million, three hundred ninety thousand, three hundred three".