21248911 has 4 divisors (see below), whose sum is σ = 21367800. Its totient is φ = 21130024.

The previous prime is 21248893. The next prime is 21248921. The reversal of 21248911 is 11984212.

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

It is a cyclic number.

It is not a de Polignac number, because 21248911 - 2⁵ = 21248879 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21248911.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21248921) 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 in 3 ways as a sum of consecutive naturals, for example, 59176 + ... + 59533.

It is an arithmetic number, because the mean of its divisors is an integer number (5341950).

Almost surely, 2^21248911 is an apocalyptic number.

21248911 is the 2062-nd centered decagonal number.

21248911 is a deficient number, since it is larger than the sum of its proper divisors (118889).

21248911 is a wasteful number, since it uses less digits than its factorization.

21248911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118888.

The product of its digits is 1152, while the sum is 28.

The square root of 21248911 is about 4609.6541084988. The cubic root of 21248911 is about 276.9781812370.

The spelling of 21248911 in words is "twenty-one million, two hundred forty-eight thousand, nine hundred eleven".