21630028 has 24 divisors (see below), whose sum is σ = 45142272. Its totient is φ = 8866704.

The previous prime is 21630019. The next prime is 21630031. The reversal of 21630028 is 82003612.

It is a super-2 number, since 2×21630028² = 935716222561568, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21629990 and 21630008.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16150 + ... + 17437.

It is an arithmetic number, because the mean of its divisors is an integer number (1880928).

Almost surely, 2^21630028 is an apocalyptic number.

21630028 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21630028 is an abundant number, since it is smaller than the sum of its proper divisors (23512244).

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

21630028 is a wasteful number, since it uses less digits than its factorization.

21630028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33621 (or 33619 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 21630028 is about 4650.8093919231. The cubic root of 21630028 is about 278.6243236209.

The spelling of 21630028 in words is "twenty-one million, six hundred thirty thousand, twenty-eight".