21812428 has 48 divisors (see below), whose sum is σ = 44640288. Its totient is φ = 9292800.

The previous prime is 21812419. The next prime is 21812429. The reversal of 21812428 is 82421812.

It is a junction number, because it is equal to n+sod(n) for n = 21812396 and 21812405.

It is not an unprimeable number, because it can be changed into a prime (21812429) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 90388 + ... + 90628.

It is an arithmetic number, because the mean of its divisors is an integer number (930006).

Almost surely, 2^21812428 is an apocalyptic number.

It is an amenable number.

21812428 is an abundant number, since it is smaller than the sum of its proper divisors (22827860).

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

21812428 is a wasteful number, since it uses less digits than its factorization.

21812428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 295 (or 271 counting only the distinct ones).

The product of its digits is 2048, while the sum is 28.

The square root of 21812428 is about 4670.3777149177. The cubic root of 21812428 is about 279.4053195094.

The spelling of 21812428 in words is "twenty-one million, eight hundred twelve thousand, four hundred twenty-eight".