21058724 has 12 divisors (see below), whose sum is σ = 37088604. Its totient is φ = 10461984.

The previous prime is 21058721. The next prime is 21058729. The reversal of 21058724 is 42785012.

It can be written as a sum of positive squares in 2 ways, for example, as 11560000 + 9498724 = 3400^2 + 3082^2 .

It is not an unprimeable number, because it can be changed into a prime (21058721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16139 + ... + 17394.

It is an arithmetic number, because the mean of its divisors is an integer number (3090717).

Almost surely, 2^21058724 is an apocalyptic number.

It is an amenable number.

21058724 is a deficient number, since it is larger than the sum of its proper divisors (16029880).

21058724 is a wasteful number, since it uses less digits than its factorization.

21058724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33694 (or 33692 counting only the distinct ones).

The product of its (nonzero) digits is 4480, while the sum is 29.

The square root of 21058724 is about 4588.9785355785. The cubic root of 21058724 is about 276.1493450649.

The spelling of 21058724 in words is "twenty-one million, fifty-eight thousand, seven hundred twenty-four".