21398503 has 16 divisors (see below), whose sum is σ = 25885440. Its totient is φ = 17280000.

The previous prime is 21398497. The next prime is 21398513. The reversal of 21398503 is 30589312.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21398503 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21398513) 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 in 15 ways as a sum of consecutive naturals, for example, 33063 + ... + 33703.

It is an arithmetic number, because the mean of its divisors is an integer number (1617840).

Almost surely, 2^21398503 is an apocalyptic number.

21398503 is a deficient number, since it is larger than the sum of its proper divisors (4486937).

21398503 is a wasteful number, since it uses less digits than its factorization.

21398503 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 918.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 21398503 is about 4625.8515972737. The cubic root of 21398503 is about 277.6266359222.

The spelling of 21398503 in words is "twenty-one million, three hundred ninety-eight thousand, five hundred three".