21556343 has 4 divisors (see below), whose sum is σ = 21625968. Its totient is φ = 21486720.

The previous prime is 21556321. The next prime is 21556349. The reversal of 21556343 is 34365512.

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 21556343 - 2¹² = 21552247 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 (21556349) 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, 34346 + ... + 34967.

It is an arithmetic number, because the mean of its divisors is an integer number (5406492).

Almost surely, 2^21556343 is an apocalyptic number.

21556343 is a deficient number, since it is larger than the sum of its proper divisors (69625).

21556343 is an equidigital number, since it uses as much as digits as its factorization.

21556343 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69624.

The product of its digits is 10800, while the sum is 29.

The square root of 21556343 is about 4642.8808944447. The cubic root of 21556343 is about 278.3075758332.

The spelling of 21556343 in words is "twenty-one million, five hundred fifty-six thousand, three hundred forty-three".