21432220 has 24 divisors (see below), whose sum is σ = 45108000. Its totient is φ = 8553792.

The previous prime is 21432211. The next prime is 21432233. The reversal of 21432220 is 2223412.

It is a junction number, because it is equal to n+sod(n) for n = 21432194 and 21432203.

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, 11086 + ... + 12874.

It is an arithmetic number, because the mean of its divisors is an integer number (1879500).

Almost surely, 2^21432220 is an apocalyptic number.

21432220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21432220 is an abundant number, since it is smaller than the sum of its proper divisors (23675780).

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

21432220 is a wasteful number, since it uses less digits than its factorization.

21432220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2397 (or 2395 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 21432220 is about 4629.4945728449. The cubic root of 21432220 is about 277.7723754801.

Adding to 21432220 its reverse (2223412), we get a palindrome (23655632).

The spelling of 21432220 in words is "twenty-one million, four hundred thirty-two thousand, two hundred twenty".