21890028 has 12 divisors (see below), whose sum is σ = 51076760. Its totient is φ = 7296672.

The previous prime is 21889993. The next prime is 21890047. The reversal of 21890028 is 82009812.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 21889977 and 21890004.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 912073 + ... + 912096.

Almost surely, 2^21890028 is an apocalyptic number.

It is an amenable number.

21890028 is an abundant number, since it is smaller than the sum of its proper divisors (29186732).

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

21890028 is a wasteful number, since it uses less digits than its factorization.

21890028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1824176 (or 1824174 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 30.

The square root of 21890028 is about 4678.6780184150. The cubic root of 21890028 is about 279.7362652691.

The spelling of 21890028 in words is "twenty-one million, eight hundred ninety thousand, twenty-eight".