21890084 has 24 divisors (see below), whose sum is σ = 41028120. Its totient is φ = 10182656.

The previous prime is 21890083. The next prime is 21890093. The reversal of 21890084 is 48009812.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 6400 + 21883684 = 80^2 + 4678^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21890084.

It is not an unprimeable number, because it can be changed into a prime (21890083) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4244 + ... + 7860.

It is an arithmetic number, because the mean of its divisors is an integer number (1709505).

Almost surely, 2^21890084 is an apocalyptic number.

It is an amenable number.

21890084 is a deficient number, since it is larger than the sum of its proper divisors (19138036).

21890084 is a wasteful number, since it uses less digits than its factorization.

21890084 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3727 (or 3725 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 21890084 is about 4678.6840030077. The cubic root of 21890084 is about 279.7365038133.

Adding to 21890084 its reverse (48009812), we get a palindrome (69899896).

The spelling of 21890084 in words is "twenty-one million, eight hundred ninety thousand, eighty-four".