21339685 has 4 divisors (see below), whose sum is σ = 25607628. Its totient is φ = 17071744.

The previous prime is 21339677. The next prime is 21339733. The reversal of 21339685 is 58693312.

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

It can be written as a sum of positive squares in 2 ways, for example, as 9928801 + 11410884 = 3151^2 + 3378^2 .

It is a cyclic number.

It is not a de Polignac number, because 21339685 - 2³ = 21339677 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2133964 + ... + 2133973.

It is an arithmetic number, because the mean of its divisors is an integer number (6401907).

Almost surely, 2^21339685 is an apocalyptic number.

It is an amenable number.

21339685 is a deficient number, since it is larger than the sum of its proper divisors (4267943).

21339685 is an equidigital number, since it uses as much as digits as its factorization.

21339685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4267942.

The product of its digits is 38880, while the sum is 37.

The square root of 21339685 is about 4619.4896904312. The cubic root of 21339685 is about 277.3720320071.

The spelling of 21339685 in words is "twenty-one million, three hundred thirty-nine thousand, six hundred eighty-five".