21820938 has 32 divisors (see below), whose sum is σ = 45178560. Its totient is φ = 7021440.

The previous prime is 21820937. The next prime is 21820957. The reversal of 21820938 is 83902812.

It is a junction number, because it is equal to n+sod(n) for n = 21820899 and 21820908.

It is not an unprimeable number, because it can be changed into a prime (21820933) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25908 + ... + 26736.

It is an arithmetic number, because the mean of its divisors is an integer number (1411830).

Almost surely, 2^21820938 is an apocalyptic number.

21820938 is an abundant number, since it is smaller than the sum of its proper divisors (23357622).

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

21820938 is a wasteful number, since it uses less digits than its factorization.

21820938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 982.

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 21820938 is about 4671.2886872896. The cubic root of 21820938 is about 279.4416509395.

The spelling of 21820938 in words is "twenty-one million, eight hundred twenty thousand, nine hundred thirty-eight".