21820983 has 4 divisors (see below), whose sum is σ = 29094648. Its totient is φ = 14547320.

The previous prime is 21820957. The next prime is 21820991. The reversal of 21820983 is 38902812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21820983 is a prime.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 3636828 + ... + 3636833.

It is an arithmetic number, because the mean of its divisors is an integer number (7273662).

Almost surely, 2^21820983 is an apocalyptic number.

21820983 is a deficient number, since it is larger than the sum of its proper divisors (7273665).

21820983 is an equidigital number, since it uses as much as digits as its factorization.

21820983 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7273664.

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

The square root of 21820983 is about 4671.2935039451. The cubic root of 21820983 is about 279.4418430313.

The spelling of 21820983 in words is "twenty-one million, eight hundred twenty thousand, nine hundred eighty-three".