21750730 has 8 divisors (see below), whose sum is σ = 39151332. Its totient is φ = 8700288.

The previous prime is 21750721. The next prime is 21750737. The reversal of 21750730 is 3705712.

It can be written as a sum of positive squares in 2 ways, for example, as 19018321 + 2732409 = 4361^2 + 1653^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 21750695 and 21750704.

It is not an unprimeable number, because it can be changed into a prime (21750737) 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, 1087527 + ... + 1087546.

Almost surely, 2^21750730 is an apocalyptic number.

21750730 is a deficient number, since it is larger than the sum of its proper divisors (17400602).

21750730 is a wasteful number, since it uses less digits than its factorization.

21750730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2175080.

The product of its (nonzero) digits is 1470, while the sum is 25.

The square root of 21750730 is about 4663.7677901028. The cubic root of 21750730 is about 279.1416314769.

The spelling of 21750730 in words is "twenty-one million, seven hundred fifty thousand, seven hundred thirty".