21508039 has 8 divisors (see below), whose sum is σ = 24877440. Its totient is φ = 18212856.

The previous prime is 21508031. The next prime is 21508061. The reversal of 21508039 is 93080512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21508039 - 2³ = 21508031 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21507998 and 21508016.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21508031) 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 7 ways as a sum of consecutive naturals, for example, 17929 + ... + 19090.

It is an arithmetic number, because the mean of its divisors is an integer number (3109680).

Almost surely, 2^21508039 is an apocalyptic number.

21508039 is a deficient number, since it is larger than the sum of its proper divisors (3369401).

21508039 is an equidigital number, since it uses as much as digits as its factorization.

21508039 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37109.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 21508039 is about 4637.6760343948. The cubic root of 21508039 is about 278.0995408081.

The spelling of 21508039 in words is "twenty-one million, five hundred eight thousand, thirty-nine".