21569983 has 2 divisors, whose sum is σ = 21569984. Its totient is φ = 21569982.

The previous prime is 21569981. The next prime is 21570011. The reversal of 21569983 is 38996512.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21569983 - 2¹ = 21569981 is a prime.

Together with 21569981, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21569981) by changing a digit.

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 as a sum of consecutive naturals, namely, 10784991 + 10784992.

It is an arithmetic number, because the mean of its divisors is an integer number (10784992).

Almost surely, 2^21569983 is an apocalyptic number.

21569983 is a deficient number, since it is larger than the sum of its proper divisors (1).

21569983 is an equidigital number, since it uses as much as digits as its factorization.

21569983 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 116640, while the sum is 43.

The square root of 21569983 is about 4644.3495777127. The cubic root of 21569983 is about 278.3662641265.

The spelling of 21569983 in words is "twenty-one million, five hundred sixty-nine thousand, nine hundred eighty-three".