21316730 has 16 divisors (see below), whose sum is σ = 38897064. Its totient is φ = 8409600.

The previous prime is 21316723. The next prime is 21316739. The reversal of 21316730 is 3761312.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 15976009 + 5340721 = 3997^2 + 2311^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21316696 and 21316705.

It is not an unprimeable number, because it can be changed into a prime (21316739) 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, 13871 + ... + 15330.

Almost surely, 2^21316730 is an apocalyptic number.

21316730 is a deficient number, since it is larger than the sum of its proper divisors (17580334).

21316730 is a wasteful number, since it uses less digits than its factorization.

21316730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29281.

The product of its (nonzero) digits is 756, while the sum is 23.

The square root of 21316730 is about 4617.0044401105. The cubic root of 21316730 is about 277.2725403890.

The spelling of 21316730 in words is "twenty-one million, three hundred sixteen thousand, seven hundred thirty".