21027647 has 4 divisors (see below), whose sum is σ = 21046776. Its totient is φ = 21008520.

The previous prime is 21027637. The next prime is 21027649. The reversal of 21027647 is 74672012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21027647 - 2²² = 16833343 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 (21027649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7808 + ... + 10149.

It is an arithmetic number, because the mean of its divisors is an integer number (5261694).

Almost surely, 2^21027647 is an apocalyptic number.

21027647 is a deficient number, since it is larger than the sum of its proper divisors (19129).

21027647 is a wasteful number, since it uses less digits than its factorization.

21027647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19128.

The product of its (nonzero) digits is 4704, while the sum is 29.

The square root of 21027647 is about 4585.5912377795. The cubic root of 21027647 is about 276.0134375240.

Adding to 21027647 its reverse (74672012), we get a palindrome (95699659).

The spelling of 21027647 in words is "twenty-one million, twenty-seven thousand, six hundred forty-seven".