21403320 has 32 divisors (see below), whose sum is σ = 64210320. Its totient is φ = 5707520.

The previous prime is 21403313. The next prime is 21403337. The reversal of 21403320 is 2330412.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21403320.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 89061 + ... + 89300.

Almost surely, 2^21403320 is an apocalyptic number.

21403320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21403320 is an abundant number, since it is smaller than the sum of its proper divisors (42807000).

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

21403320 is a wasteful number, since it uses less digits than its factorization.

21403320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 178375 (or 178371 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 15.

The square root of 21403320 is about 4626.3722288636. The cubic root of 21403320 is about 277.6474664630.

Adding to 21403320 its reverse (2330412), we get a palindrome (23733732).

It can be divided in two parts, 2140 and 3320, that added together give a triangular number (5460 = T₁₀₄).

The spelling of 21403320 in words is "twenty-one million, four hundred three thousand, three hundred twenty".