21220620 has 24 divisors (see below), whose sum is σ = 59417904. Its totient is φ = 5658816.

The previous prime is 21220613. The next prime is 21220627. The reversal of 21220620 is 2602212.

It is an interprime number because it is at equal distance from previous prime (21220613) and next prime (21220627).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21220620.

It is not an unprimeable number, because it can be changed into a prime (21220627) 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 7 ways as a sum of consecutive naturals, for example, 176779 + ... + 176898.

It is an arithmetic number, because the mean of its divisors is an integer number (2475746).

Almost surely, 2^21220620 is an apocalyptic number.

21220620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21220620 is an abundant number, since it is smaller than the sum of its proper divisors (38197284).

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

21220620 is a wasteful number, since it uses less digits than its factorization.

21220620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 353689 (or 353687 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21220620 is about 4606.5844179826. The cubic root of 21220620 is about 276.8552028573.

Adding to 21220620 its reverse (2602212), we get a palindrome (23822832).

It can be divided in two parts, 212206 and 20, that added together give a triangular number (212226 = T₆₅₁).

The spelling of 21220620 in words is "twenty-one million, two hundred twenty thousand, six hundred twenty".