21997583 has 4 divisors (see below), whose sum is σ = 22081488. Its totient is φ = 21913680.

The previous prime is 21997579. The next prime is 21997589. The reversal of 21997583 is 38579912.

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

It is a cyclic number.

It is not a de Polignac number, because 21997583 - 2² = 21997579 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21997589) 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 in 3 ways as a sum of consecutive naturals, for example, 41558 + ... + 42083.

It is an arithmetic number, because the mean of its divisors is an integer number (5520372).

Almost surely, 2^21997583 is an apocalyptic number.

21997583 is a deficient number, since it is larger than the sum of its proper divisors (83905).

21997583 is an equidigital number, since it uses as much as digits as its factorization.

21997583 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83904.

The product of its digits is 136080, while the sum is 44.

The square root of 21997583 is about 4690.1580996806. The cubic root of 21997583 is about 280.1936712821.

The spelling of 21997583 in words is "twenty-one million, nine hundred ninety-seven thousand, five hundred eighty-three".