21723784 has 16 divisors (see below), whose sum is σ = 42137100. Its totient is φ = 10487232.

The previous prime is 21723763. The next prime is 21723791. The reversal of 21723784 is 48732712.

It can be written as a sum of positive squares in 2 ways, for example, as 18404100 + 3319684 = 4290^2 + 1822^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46587 + ... + 47050.

Almost surely, 2^21723784 is an apocalyptic number.

It is an amenable number.

21723784 is a deficient number, since it is larger than the sum of its proper divisors (20413316).

21723784 is a wasteful number, since it uses less digits than its factorization.

21723784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93672 (or 93668 counting only the distinct ones).

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

The square root of 21723784 is about 4660.8780288697. The cubic root of 21723784 is about 279.0263118430.

The spelling of 21723784 in words is "twenty-one million, seven hundred twenty-three thousand, seven hundred eighty-four".