21643350 has 24 divisors (see below), whose sum is σ = 53675880. Its totient is φ = 5771520.

The previous prime is 21643333. The next prime is 21643351. The reversal of 21643350 is 5334612.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21643350.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21643351) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 71995 + ... + 72294.

It is an arithmetic number, because the mean of its divisors is an integer number (2236495).

Almost surely, 2^21643350 is an apocalyptic number.

21643350 is an abundant number, since it is smaller than the sum of its proper divisors (32032530).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21643350 is a wasteful number, since it uses less digits than its factorization.

21643350 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144304 (or 144299 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 24.

The square root of 21643350 is about 4652.2413952846. The cubic root of 21643350 is about 278.6815137373.

Adding to 21643350 its reverse (5334612), we get a palindrome (26977962).

It can be divided in two parts, 216 and 43350, that multiplied together give a square (9363600 = 3060²).

The spelling of 21643350 in words is "twenty-one million, six hundred forty-three thousand, three hundred fifty".