21753830 has 32 divisors (see below), whose sum is σ = 45121536. Its totient is φ = 7396704.

The previous prime is 21753827. The next prime is 21753839. The reversal of 21753830 is 3835712.

21753830 = T₄₈₆ + T₄₈₇ + ... + T₆₂₅.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21753793 and 21753802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21753839) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7667 + ... + 10113.

It is an arithmetic number, because the mean of its divisors is an integer number (1410048).

Almost surely, 2^21753830 is an apocalyptic number.

21753830 is an abundant number, since it is smaller than the sum of its proper divisors (23367706).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21753830 is a wasteful number, since it uses less digits than its factorization.

21753830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2588.

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

The square root of 21753830 is about 4664.1001275702. The cubic root of 21753830 is about 279.1548923031.

The spelling of 21753830 in words is "twenty-one million, seven hundred fifty-three thousand, eight hundred thirty".