21400730 has 16 divisors (see below), whose sum is σ = 41484744. Its totient is φ = 7901760.

The previous prime is 21400723. The next prime is 21400747. The reversal of 21400730 is 3700412.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 14984641 + 6416089 = 3871^2 + 2533^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21400699 and 21400708.

It is an unprimeable number.

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, 82181 + ... + 82440.

Almost surely, 2^21400730 is an apocalyptic number.

21400730 is a deficient number, since it is larger than the sum of its proper divisors (20084014).

21400730 is a wasteful number, since it uses less digits than its factorization.

21400730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164641.

The product of its (nonzero) digits is 168, while the sum is 17.

The square root of 21400730 is about 4626.0923034457. The cubic root of 21400730 is about 277.6362667060.

The spelling of 21400730 in words is "twenty-one million, four hundred thousand, seven hundred thirty".