21336457 has 8 divisors (see below), whose sum is σ = 22058696. Its totient is φ = 20621952.

The previous prime is 21336409. The next prime is 21336467. The reversal of 21336457 is 75463312.

It can be written as a sum of positive squares in 4 ways, for example, as 1301881 + 20034576 = 1141^2 + 4476^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21336457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21336407) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3973 + ... + 7645.

It is an arithmetic number, because the mean of its divisors is an integer number (2757337).

Almost surely, 2^21336457 is an apocalyptic number.

It is an amenable number.

21336457 is a deficient number, since it is larger than the sum of its proper divisors (722239).

21336457 is a wasteful number, since it uses less digits than its factorization.

21336457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3867.

The product of its digits is 15120, while the sum is 31.

The square root of 21336457 is about 4619.1402879757. The cubic root of 21336457 is about 277.3580455140.

Adding to 21336457 its reverse (75463312), we get a palindrome (96799769).

The spelling of 21336457 in words is "twenty-one million, three hundred thirty-six thousand, four hundred fifty-seven".