21318456 has 32 divisors (see below), whose sum is σ = 56102400. Its totient is φ = 6732000.

The previous prime is 21318449. The next prime is 21318461. The reversal of 21318456 is 65481312.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22920 + ... + 23831.

It is an arithmetic number, because the mean of its divisors is an integer number (1753200).

Almost surely, 2^21318456 is an apocalyptic number.

It is an amenable number.

21318456 is an abundant number, since it is smaller than the sum of its proper divisors (34783944).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21318456 is a wasteful number, since it uses less digits than its factorization.

21318456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46779 (or 46775 counting only the distinct ones).

The product of its digits is 5760, while the sum is 30.

The square root of 21318456 is about 4617.1913540593. The cubic root of 21318456 is about 277.2800237051.

Adding to 21318456 its reverse (65481312), we get a palindrome (86799768).

The spelling of 21318456 in words is "twenty-one million, three hundred eighteen thousand, four hundred fifty-six".