21335220 has 36 divisors (see below), whose sum is σ = 64717380. Its totient is φ = 5689344.

The previous prime is 21335219. The next prime is 21335231. The reversal of 21335220 is 2253312.

It can be written as a sum of positive squares in 2 ways, for example, as 9474084 + 11861136 = 3078^2 + 3444^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×21335220² = 910383224896800, which contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 21335193 and 21335202.

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 59085 + ... + 59444.

It is an arithmetic number, because the mean of its divisors is an integer number (1797705).

Almost surely, 2^21335220 is an apocalyptic number.

21335220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21335220 is an abundant number, since it is smaller than the sum of its proper divisors (43382160).

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

21335220 is a wasteful number, since it uses less digits than its factorization.

21335220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118544 (or 118539 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 18.

The square root of 21335220 is about 4619.0063866594. The cubic root of 21335220 is about 277.3526853843.

Adding to 21335220 its reverse (2253312), we get a palindrome (23588532).

It can be divided in two parts, 21 and 335220, that added together give a square (335241 = 579²).

The spelling of 21335220 in words is "twenty-one million, three hundred thirty-five thousand, two hundred twenty".