21253982 has 4 divisors (see below), whose sum is σ = 31880976. Its totient is φ = 10626990.

The previous prime is 21253979. The next prime is 21253987. The reversal of 21253982 is 28935212.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253987) by changing a digit.

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, 5313494 + ... + 5313497.

It is an arithmetic number, because the mean of its divisors is an integer number (7970244).

Almost surely, 2^21253982 is an apocalyptic number.

21253982 is a deficient number, since it is larger than the sum of its proper divisors (10626994).

21253982 is a wasteful number, since it uses less digits than its factorization.

21253982 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10626993.

The product of its digits is 8640, while the sum is 32.

The square root of 21253982 is about 4610.2041169562. The cubic root of 21253982 is about 277.0002128702. Note that the first 3 decimals are identical.

The spelling of 21253982 in words is "twenty-one million, two hundred fifty-three thousand, nine hundred eighty-two".