21678043 has 4 divisors (see below), whose sum is σ = 22953240. Its totient is φ = 20402848.

The previous prime is 21678037. The next prime is 21678049. The reversal of 21678043 is 34087612.

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

It is an interprime number because it is at equal distance from previous prime (21678037) and next prime (21678049).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21678043 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21677996 and 21678014.

It is not an unprimeable number, because it can be changed into a prime (21678049) 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, 637573 + ... + 637606.

It is an arithmetic number, because the mean of its divisors is an integer number (5738310).

Almost surely, 2^21678043 is an apocalyptic number.

21678043 is a deficient number, since it is larger than the sum of its proper divisors (1275197).

21678043 is a wasteful number, since it uses less digits than its factorization.

21678043 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1275196.

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

The square root of 21678043 is about 4655.9685351170. The cubic root of 21678043 is about 278.8303375322.

The spelling of 21678043 in words is "twenty-one million, six hundred seventy-eight thousand, forty-three".