21002355 has 32 divisors (see below), whose sum is σ = 40734720. Its totient is φ = 10182240.

The previous prime is 21002341. The next prime is 21002357. The reversal of 21002355 is 55320012.

It is a happy number.

It is not a de Polignac number, because 21002355 - 2⁵ = 21002323 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21002357) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5587 + ... + 8556.

It is an arithmetic number, because the mean of its divisors is an integer number (1272960).

Almost surely, 2^21002355 is an apocalyptic number.

21002355 is a deficient number, since it is larger than the sum of its proper divisors (19732365).

21002355 is a wasteful number, since it uses less digits than its factorization.

21002355 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14168 (or 14162 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 18.

The square root of 21002355 is about 4582.8326393182. The cubic root of 21002355 is about 275.9027303739.

Adding to 21002355 its reverse (55320012), we get a palindrome (76322367).

The spelling of 21002355 in words is "twenty-one million, two thousand, three hundred fifty-five".