21508983 has 10 divisors (see below), whose sum is σ = 32130824. Its totient is φ = 14339268.

The previous prime is 21508973. The next prime is 21509003. The reversal of 21508983 is 38980512.

It is not a de Polignac number, because 21508983 - 2⁶ = 21508919 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 (21508973) 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 9 ways as a sum of consecutive naturals, for example, 132691 + ... + 132852.

Almost surely, 2^21508983 is an apocalyptic number.

21508983 is a deficient number, since it is larger than the sum of its proper divisors (10621841).

21508983 is an equidigital number, since it uses as much as digits as its factorization.

21508983 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265555 (or 265546 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 21508983 is about 4637.7778083906. Note that the first 3 decimals coincide. The cubic root of 21508983 is about 278.1036093973.

The spelling of 21508983 in words is "twenty-one million, five hundred eight thousand, nine hundred eighty-three".