21002238 has 24 divisors (see below), whose sum is σ = 45621576. Its totient is φ = 6982800.

The previous prime is 21002231. The next prime is 21002251. The reversal of 21002238 is 83220012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21002238.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002231) 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, 7033 + ... + 9563.

It is an arithmetic number, because the mean of its divisors is an integer number (1900899).

Almost surely, 2^21002238 is an apocalyptic number.

21002238 is an abundant number, since it is smaller than the sum of its proper divisors (24619338).

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

21002238 is a wasteful number, since it uses less digits than its factorization.

21002238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3000 (or 2997 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21002238 is about 4582.8198742696. The cubic root of 21002238 is about 275.9022180397.

The spelling of 21002238 in words is "twenty-one million, two thousand, two hundred thirty-eight".