21819028 has 24 divisors (see below), whose sum is σ = 47605824. Its totient is φ = 8500800.

The previous prime is 21819001. The next prime is 21819059. The reversal of 21819028 is 82091812.

It is a happy number.

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35113 + ... + 35728.

It is an arithmetic number, because the mean of its divisors is an integer number (1983576).

Almost surely, 2^21819028 is an apocalyptic number.

21819028 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21819028 is an abundant number, since it is smaller than the sum of its proper divisors (25786796).

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

21819028 is a wasteful number, since it uses less digits than its factorization.

21819028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70863 (or 70861 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 21819028 is about 4671.0842424431. The cubic root of 21819028 is about 279.4334974690.

The spelling of 21819028 in words is "twenty-one million, eight hundred nineteen thousand, twenty-eight".