21228037 has 8 divisors (see below), whose sum is σ = 22158360. Its totient is φ = 20317440.

The previous prime is 21228017. The next prime is 21228041. The reversal of 21228037 is 73082212.

It can be written as a sum of positive squares in 4 ways, for example, as 443556 + 20784481 = 666^2 + 4559^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21228037 - 2¹¹ = 21225989 is a prime.

It is a Duffinian number.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21228007) 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, 2712 + ... + 7057.

It is an arithmetic number, because the mean of its divisors is an integer number (2769795).

Almost surely, 2^21228037 is an apocalyptic number.

It is an amenable number.

21228037 is a deficient number, since it is larger than the sum of its proper divisors (930323).

21228037 is an equidigital number, since it uses as much as digits as its factorization.

21228037 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9863.

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 21228037 is about 4607.3893909675. The cubic root of 21228037 is about 276.8874544417.

It can be divided in two parts, 212 and 28037, that multiplied together give a square (5943844 = 2438²).

The spelling of 21228037 in words is "twenty-one million, two hundred twenty-eight thousand, thirty-seven".