21208464 has 60 divisors (see below), whose sum is σ = 61281792. Its totient is φ = 6840000.

The previous prime is 21208441. The next prime is 21208487. The reversal of 21208464 is 46480212.

It is an interprime number because it is at equal distance from previous prime (21208441) and next prime (21208487).

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 11 ways as a sum of consecutive naturals, for example, 2089 + ... + 6839.

Almost surely, 2^21208464 is an apocalyptic number.

21208464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21208464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30640896).

21208464 is an abundant number, since it is smaller than the sum of its proper divisors (40073328).

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

21208464 is a wasteful number, since it uses less digits than its factorization.

21208464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4796 (or 4787 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 27.

The square root of 21208464 is about 4605.2648132328. The cubic root of 21208464 is about 276.8023282685.

Adding to 21208464 its reverse (46480212), we get a palindrome (67688676).

The spelling of 21208464 in words is "twenty-one million, two hundred eight thousand, four hundred sixty-four".