21802530 has 16 divisors (see below), whose sum is σ = 52326144. Its totient is φ = 5814000.

The previous prime is 21802513. The next prime is 21802531. The reversal of 21802530 is 3520812.

It is a junction number, because it is equal to n+sod(n) for n = 21802497 and 21802506.

It is not an unprimeable number, because it can be changed into a prime (21802531) 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 7 ways as a sum of consecutive naturals, for example, 363346 + ... + 363405.

It is an arithmetic number, because the mean of its divisors is an integer number (3270384).

Almost surely, 2^21802530 is an apocalyptic number.

21802530 is an abundant number, since it is smaller than the sum of its proper divisors (30523614).

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

21802530 is a wasteful number, since it uses less digits than its factorization.

21802530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 726761.

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21802530 is about 4669.3179373437. The cubic root of 21802530 is about 279.3630504526.

The spelling of 21802530 in words is "twenty-one million, eight hundred two thousand, five hundred thirty".