21828761 has 4 divisors (see below), whose sum is σ = 22198800. Its totient is φ = 21458724.

The previous prime is 21828733. The next prime is 21828767. The reversal of 21828761 is 16782812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21828761 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21828767) by changing a digit.

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, 184931 + ... + 185048.

It is an arithmetic number, because the mean of its divisors is an integer number (5549700).

Almost surely, 2^21828761 is an apocalyptic number.

It is an amenable number.

21828761 is a deficient number, since it is larger than the sum of its proper divisors (370039).

21828761 is an equidigital number, since it uses as much as digits as its factorization.

21828761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 370038.

The product of its digits is 10752, while the sum is 35.

The square root of 21828761 is about 4672.1259614869. The cubic root of 21828761 is about 279.4750410539.

The spelling of 21828761 in words is "twenty-one million, eight hundred twenty-eight thousand, seven hundred sixty-one".