21220470 has 24 divisors (see below), whose sum is σ = 55173456. Its totient is φ = 5658768.

The previous prime is 21220429. The next prime is 21220477. The reversal of 21220470 is 7402212.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220477) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 117802 + ... + 117981.

It is an arithmetic number, because the mean of its divisors is an integer number (2298894).

Almost surely, 2^21220470 is an apocalyptic number.

21220470 is an abundant number, since it is smaller than the sum of its proper divisors (33952986).

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

21220470 is a wasteful number, since it uses less digits than its factorization.

21220470 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 235796 (or 235793 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 18.

The square root of 21220470 is about 4606.5681369106. The cubic root of 21220470 is about 276.8545505299.

Adding to 21220470 its reverse (7402212), we get a palindrome (28622682).

The spelling of 21220470 in words is "twenty-one million, two hundred twenty thousand, four hundred seventy".