21228471 has 24 divisors (see below), whose sum is σ = 34909056. Its totient is φ = 12305040.

The previous prime is 21228469. The next prime is 21228509. The reversal of 21228471 is 17482212.

It is not a de Polignac number, because 21228471 - 2¹ = 21228469 is a prime.

It is a super-3 number, since 3×21228471³ (a number of 23 digits) contains 333 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21228421) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2385 + ... + 6938.

It is an arithmetic number, because the mean of its divisors is an integer number (1454544).

Almost surely, 2^21228471 is an apocalyptic number.

21228471 is a deficient number, since it is larger than the sum of its proper divisors (13680585).

21228471 is a wasteful number, since it uses less digits than its factorization.

21228471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9363 (or 9360 counting only the distinct ones).

The product of its digits is 1792, while the sum is 27.

The square root of 21228471 is about 4607.4364889817. The cubic root of 21228471 is about 276.8893413854.

The spelling of 21228471 in words is "twenty-one million, two hundred twenty-eight thousand, four hundred seventy-one".