21890838 has 16 divisors (see below), whose sum is σ = 43946496. Its totient is φ = 7269480.

The previous prime is 21890807. The next prime is 21890839. The reversal of 21890838 is 83809812.

It is a junction number, because it is equal to n+sod(n) for n = 21890796 and 21890805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21890839) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5106 + ... + 8357.

It is an arithmetic number, because the mean of its divisors is an integer number (2746656).

Almost surely, 2^21890838 is an apocalyptic number.

21890838 is an abundant number, since it is smaller than the sum of its proper divisors (22055658).

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

21890838 is a wasteful number, since it uses less digits than its factorization.

21890838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13739.

The product of its (nonzero) digits is 27648, while the sum is 39.

The square root of 21890838 is about 4678.7645805276. The cubic root of 21890838 is about 279.7397156009.

The spelling of 21890838 in words is "twenty-one million, eight hundred ninety thousand, eight hundred thirty-eight".