21981230 has 16 divisors (see below), whose sum is σ = 39952224. Its totient is φ = 8706720.

The previous prime is 21981229. The next prime is 21981251. The reversal of 21981230 is 3218912.

It is a self number, because there is not a number n which added to its sum of digits gives 21981230.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9641 + ... + 11700.

It is an arithmetic number, because the mean of its divisors is an integer number (2497014).

Almost surely, 2^21981230 is an apocalyptic number.

21981230 is a deficient number, since it is larger than the sum of its proper divisors (17970994).

21981230 is a wasteful number, since it uses less digits than its factorization.

21981230 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21451.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 21981230 is about 4688.4144441378. The cubic root of 21981230 is about 280.1242220916.

The spelling of 21981230 in words is "twenty-one million, nine hundred eighty-one thousand, two hundred thirty".