21135447 has 6 divisors (see below), whose sum is σ = 30528992. Its totient is φ = 14090292.

The previous prime is 21135431. The next prime is 21135449. The reversal of 21135447 is 74453112.

21135447 is a `hidden beast` number, since 2 + 113 + 544 + 7 = 666.

It is not a de Polignac number, because 21135447 - 2⁴ = 21135431 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21135447.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21135449) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1174183 + ... + 1174200.

Almost surely, 2^21135447 is an apocalyptic number.

21135447 is a deficient number, since it is larger than the sum of its proper divisors (9393545).

21135447 is a wasteful number, since it uses less digits than its factorization.

21135447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2348389 (or 2348386 counting only the distinct ones).

The product of its digits is 3360, while the sum is 27.

The square root of 21135447 is about 4597.3304210161. The cubic root of 21135447 is about 276.4843024921.

Adding to 21135447 its reverse (74453112), we get a palindrome (95588559).

The spelling of 21135447 in words is "twenty-one million, one hundred thirty-five thousand, four hundred forty-seven".