21006339 has 16 divisors (see below), whose sum is σ = 29766528. Its totient is φ = 13131392.

The previous prime is 21006329. The next prime is 21006341. The reversal of 21006339 is 93360012.

It is a cyclic number.

It is not a de Polignac number, because 21006339 - 2⁹ = 21005827 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21006329) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17104 + ... + 18290.

It is an arithmetic number, because the mean of its divisors is an integer number (1860408).

Almost surely, 2^21006339 is an apocalyptic number.

21006339 is a deficient number, since it is larger than the sum of its proper divisors (8760189).

21006339 is a wasteful number, since it uses less digits than its factorization.

21006339 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1554.

The product of its (nonzero) digits is 972, while the sum is 24.

The square root of 21006339 is about 4583.2672843726. The cubic root of 21006339 is about 275.9201748777.

The spelling of 21006339 in words is "twenty-one million, six thousand, three hundred thirty-nine".