21787234 has 32 divisors (see below), whose sum is σ = 40836096. Its totient is φ = 8501760.

The previous prime is 21787229. The next prime is 21787237. The reversal of 21787234 is 43278712.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a self number, because there is not a number n which added to its sum of digits gives 21787234.

It is not an unprimeable number, because it can be changed into a prime (21787237) 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 15 ways as a sum of consecutive naturals, for example, 5902 + ... + 8854.

It is an arithmetic number, because the mean of its divisors is an integer number (1276128).

Almost surely, 2^21787234 is an apocalyptic number.

21787234 is a deficient number, since it is larger than the sum of its proper divisors (19048862).

21787234 is a wasteful number, since it uses less digits than its factorization.

21787234 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3010.

The product of its digits is 18816, while the sum is 34.

The square root of 21787234 is about 4667.6797233743. The cubic root of 21787234 is about 279.2977042609.

The spelling of 21787234 in words is "twenty-one million, seven hundred eighty-seven thousand, two hundred thirty-four".