21135647 has 6 divisors (see below), whose sum is σ = 22886712. Its totient is φ = 19509672.

The previous prime is 21135637. The next prime is 21135649. The reversal of 21135647 is 74653112.

It is not a de Polignac number, because 21135647 - 2²² = 16941343 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21135649) 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, 62363 + ... + 62700.

It is an arithmetic number, because the mean of its divisors is an integer number (3814452).

Almost surely, 2^21135647 is an apocalyptic number.

21135647 is a deficient number, since it is larger than the sum of its proper divisors (1751065).

21135647 is a wasteful number, since it uses less digits than its factorization.

21135647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125089 (or 125076 counting only the distinct ones).

The product of its digits is 5040, while the sum is 29.

The square root of 21135647 is about 4597.3521727186. The cubic root of 21135647 is about 276.4851745924.

Adding to 21135647 its reverse (74653112), we get a palindrome (95788759).

The spelling of 21135647 in words is "twenty-one million, one hundred thirty-five thousand, six hundred forty-seven".