21787934 has 16 divisors (see below), whose sum is σ = 37453536. Its totient is φ = 9312000.

The previous prime is 21787907. The next prime is 21787939. The reversal of 21787934 is 43978712.

It is a junction number, because it is equal to n+sod(n) for n = 21787891 and 21787900.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21787939) 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 7 ways as a sum of consecutive naturals, for example, 3674 + ... + 7554.

It is an arithmetic number, because the mean of its divisors is an integer number (2340846).

Almost surely, 2^21787934 is an apocalyptic number.

21787934 is a deficient number, since it is larger than the sum of its proper divisors (15665602).

21787934 is a wasteful number, since it uses less digits than its factorization.

21787934 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4291.

The product of its digits is 84672, while the sum is 41.

The square root of 21787934 is about 4667.7547064943. The cubic root of 21787934 is about 279.3006954055.

The spelling of 21787934 in words is "twenty-one million, seven hundred eighty-seven thousand, nine hundred thirty-four".