21220606 has 16 divisors (see below), whose sum is σ = 36552960. Its totient is φ = 9137880.

The previous prime is 21220601. The next prime is 21220613. The reversal of 21220606 is 60602212.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24966 + ... + 25801.

It is an arithmetic number, because the mean of its divisors is an integer number (2284560).

Almost surely, 2^21220606 is an apocalyptic number.

21220606 is a deficient number, since it is larger than the sum of its proper divisors (15332354).

21220606 is a wasteful number, since it uses less digits than its factorization.

21220606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50799.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 21220606 is about 4606.5828984183. The cubic root of 21220606 is about 276.8551419735.

Adding to 21220606 its reverse (60602212), we get a palindrome (81822818).

The spelling of 21220606 in words is "twenty-one million, two hundred twenty thousand, six hundred six".