21083647 has 4 divisors (see below), whose sum is σ = 22705480. Its totient is φ = 19461816.

The previous prime is 21083633. The next prime is 21083669. The reversal of 21083647 is 74638012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21083647 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 (21083147) 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, 810897 + ... + 810922.

It is an arithmetic number, because the mean of its divisors is an integer number (5676370).

Almost surely, 2^21083647 is an apocalyptic number.

21083647 is a deficient number, since it is larger than the sum of its proper divisors (1621833).

21083647 is a wasteful number, since it uses less digits than its factorization.

21083647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1621832.

The product of its (nonzero) digits is 8064, while the sum is 31.

The square root of 21083647 is about 4591.6932606610. The cubic root of 21083647 is about 276.2582430332.

The spelling of 21083647 in words is "twenty-one million, eighty-three thousand, six hundred forty-seven".