21982306 has 4 divisors (see below), whose sum is σ = 32973462. Its totient is φ = 10991152.

The previous prime is 21982277. The next prime is 21982313. The reversal of 21982306 is 60328912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20331081 + 1651225 = 4509^2 + 1285^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax 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 as a sum of consecutive naturals, namely, 5495575 + ... + 5495578.

Almost surely, 2^21982306 is an apocalyptic number.

21982306 is a deficient number, since it is larger than the sum of its proper divisors (10991156).

21982306 is a wasteful number, since it uses less digits than its factorization.

21982306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10991155.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 21982306 is about 4688.5291936811. The cubic root of 21982306 is about 280.1287927904.

The spelling of 21982306 in words is "twenty-one million, nine hundred eighty-two thousand, three hundred six".