21253786 has 8 divisors (see below), whose sum is σ = 32909184. Its totient is φ = 10284060.

The previous prime is 21253763. The next prime is 21253849. The reversal of 21253786 is 68735212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 171340 + ... + 171463.

It is an arithmetic number, because the mean of its divisors is an integer number (4113648).

Almost surely, 2^21253786 is an apocalyptic number.

21253786 is a deficient number, since it is larger than the sum of its proper divisors (11655398).

21253786 is a wasteful number, since it uses less digits than its factorization.

21253786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 342836.

The product of its digits is 20160, while the sum is 34.

The square root of 21253786 is about 4610.1828597139. The cubic root of 21253786 is about 276.9993613873. Note that the first 3 decimals are identical.

Adding to 21253786 its reverse (68735212), we get a palindrome (89988998).

The spelling of 21253786 in words is "twenty-one million, two hundred fifty-three thousand, seven hundred eighty-six".