21663343 has 8 divisors (see below), whose sum is σ = 23537808. Its totient is φ = 19818624.

The previous prime is 21663337. The next prime is 21663349. The reversal of 21663343 is 34336612.

It is an interprime number because it is at equal distance from previous prime (21663337) and next prime (21663349).

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 21663343 - 2¹⁷ = 21532271 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 (21663349) 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, 5905 + ... + 8842.

It is an arithmetic number, because the mean of its divisors is an integer number (2942226).

Almost surely, 2^21663343 is an apocalyptic number.

21663343 is a deficient number, since it is larger than the sum of its proper divisors (1874465).

21663343 is a wasteful number, since it uses less digits than its factorization.

21663343 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14873.

The product of its digits is 7776, while the sum is 28.

The square root of 21663343 is about 4654.3896484931. The cubic root of 21663343 is about 278.7672978199.

Adding to 21663343 its reverse (34336612), we get a palindrome (55999955).

The spelling of 21663343 in words is "twenty-one million, six hundred sixty-three thousand, three hundred forty-three".