21358730 has 16 divisors (see below), whose sum is σ = 38498760. Its totient is φ = 8531712.

The previous prime is 21358699. The next prime is 21358739. The reversal of 21358730 is 3785312.

It can be written as a sum of positive squares in 4 ways, for example, as 18292729 + 3066001 = 4277^2 + 1751^2 .

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21358693 and 21358702.

It is not an unprimeable number, because it can be changed into a prime (21358739) 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 7 ways as a sum of consecutive naturals, for example, 12062 + ... + 13718.

Almost surely, 2^21358730 is an apocalyptic number.

21358730 is a deficient number, since it is larger than the sum of its proper divisors (17140030).

21358730 is a wasteful number, since it uses less digits than its factorization.

21358730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2953.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 21358730 is about 4621.5506055868. The cubic root of 21358730 is about 277.4545227534.

The spelling of 21358730 in words is "twenty-one million, three hundred fifty-eight thousand, seven hundred thirty".