21135715 has 8 divisors (see below), whose sum is σ = 25408800. Its totient is φ = 16877952.

The previous prime is 21135713. The next prime is 21135731. The reversal of 21135715 is 51753112.

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

It is a cyclic number.

It is not a de Polignac number, because 21135715 - 2¹ = 21135713 is a prime.

It is a super-2 number, since 2×21135715² = 893436897122450, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21135715.

It is not an unprimeable number, because it can be changed into a prime (21135713) 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, 534 + ... + 6523.

It is an arithmetic number, because the mean of its divisors is an integer number (3176100).

Almost surely, 2^21135715 is an apocalyptic number.

21135715 is a deficient number, since it is larger than the sum of its proper divisors (4273085).

21135715 is an equidigital number, since it uses as much as digits as its factorization.

21135715 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7661.

The product of its digits is 1050, while the sum is 25.

The square root of 21135715 is about 4597.3595682739. The cubic root of 21135715 is about 276.4854711052.

Adding to 21135715 its reverse (51753112), we get a palindrome (72888827).

The spelling of 21135715 in words is "twenty-one million, one hundred thirty-five thousand, seven hundred fifteen".