21856345 has 8 divisors (see below), whose sum is σ = 29974464. Its totient is φ = 14987184.

The previous prime is 21856337. The next prime is 21856349. The reversal of 21856345 is 54365812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21856345 - 2³ = 21856337 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21856345.

It is not an unprimeable number, because it can be changed into a prime (21856349) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 312199 + ... + 312268.

It is an arithmetic number, because the mean of its divisors is an integer number (3746808).

Almost surely, 2^21856345 is an apocalyptic number.

It is an amenable number.

21856345 is a deficient number, since it is larger than the sum of its proper divisors (8118119).

21856345 is an equidigital number, since it uses as much as digits as its factorization.

21856345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 624479.

The product of its digits is 28800, while the sum is 34.

The square root of 21856345 is about 4675.0770047134. The cubic root of 21856345 is about 279.5927114159.

It can be divided in two parts, 21856 and 345, that added together give a square (22201 = 149²).

The spelling of 21856345 in words is "twenty-one million, eight hundred fifty-six thousand, three hundred forty-five".