21228461 has 8 divisors (see below), whose sum is σ = 22902264. Its totient is φ = 19601920.

The previous prime is 21228451. The next prime is 21228469. The reversal of 21228461 is 16482212.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 4866436 + 16362025 = 2206^2 + 4045^2 .

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 21228461 - 2¹⁴ = 21212077 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21228461.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21228469) 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, 10880 + ... + 12681.

It is an arithmetic number, because the mean of its divisors is an integer number (2862783).

Almost surely, 2^21228461 is an apocalyptic number.

It is an amenable number.

21228461 is a deficient number, since it is larger than the sum of its proper divisors (1673803).

21228461 is a wasteful number, since it uses less digits than its factorization.

21228461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23631.

The product of its digits is 1536, while the sum is 26.

The square root of 21228461 is about 4607.4354037794. The cubic root of 21228461 is about 276.8892979077.

The spelling of 21228461 in words is "twenty-one million, two hundred twenty-eight thousand, four hundred sixty-one".