21229420 has 48 divisors (see below), whose sum is σ = 46626048. Its totient is φ = 8110080.

The previous prime is 21229409. The next prime is 21229463. The reversal of 21229420 is 2492212.

It is a junction number, because it is equal to n+sod(n) for n = 21229391 and 21229400.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 59964 + ... + 60316.

It is an arithmetic number, because the mean of its divisors is an integer number (971376).

Almost surely, 2^21229420 is an apocalyptic number.

21229420 is a gapful number since it is divisible by the number (20) 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 21229420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23313024).

21229420 is an abundant number, since it is smaller than the sum of its proper divisors (25396628).

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

21229420 is a wasteful number, since it uses less digits than its factorization.

21229420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 490 (or 488 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 21229420 is about 4607.5394735151. The cubic root of 21229420 is about 276.8934673549.

It can be divided in two parts, 21 and 229420, that added together give a square (229441 = 479²).

The spelling of 21229420 in words is "twenty-one million, two hundred twenty-nine thousand, four hundred twenty".