21337685 has 4 divisors (see below), whose sum is σ = 25605228. Its totient is φ = 17070144.

The previous prime is 21337643. The next prime is 21337717. The reversal of 21337685 is 58673312.

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 15295921 + 6041764 = 3911^2 + 2458^2 .

It is a cyclic number.

It is not a de Polignac number, because 21337685 - 2⁶ = 21337621 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, 2133764 + ... + 2133773.

It is an arithmetic number, because the mean of its divisors is an integer number (6401307).

Almost surely, 2^21337685 is an apocalyptic number.

It is an amenable number.

21337685 is a deficient number, since it is larger than the sum of its proper divisors (4267543).

21337685 is an equidigital number, since it uses as much as digits as its factorization.

21337685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4267542.

The product of its digits is 30240, while the sum is 35.

The square root of 21337685 is about 4619.2732112314. The cubic root of 21337685 is about 277.3633664403.

It can be divided in two parts, 21337 and 685, that added together give a palindrome (22022).

The spelling of 21337685 in words is "twenty-one million, three hundred thirty-seven thousand, six hundred eighty-five".