21229830 has 64 divisors (see below), whose sum is σ = 57585600. Its totient is φ = 5564160.

The previous prime is 21229829. The next prime is 21229837. The reversal of 21229830 is 3892212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 21229794 and 21229803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21229837) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 15826 + ... + 17114.

It is an arithmetic number, because the mean of its divisors is an integer number (899775).

Almost surely, 2^21229830 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21229830, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28792800).

21229830 is an abundant number, since it is smaller than the sum of its proper divisors (36355770).

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

21229830 is a wasteful number, since it uses less digits than its factorization.

21229830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1366 (or 1360 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21229830 is about 4607.5839655941. The cubic root of 21229830 is about 276.8952498748.

The spelling of 21229830 in words is "twenty-one million, two hundred twenty-nine thousand, eight hundred thirty".