21143730 has 32 divisors (see below), whose sum is σ = 51321600. Its totient is φ = 5574272.

The previous prime is 21143723. The next prime is 21143747. The reversal of 21143730 is 3734112.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21143697 and 21143706.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1290 + ... + 6629.

It is an arithmetic number, because the mean of its divisors is an integer number (1603800).

Almost surely, 2^21143730 is an apocalyptic number.

21143730 is an abundant number, since it is smaller than the sum of its proper divisors (30177870).

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

21143730 is a wasteful number, since it uses less digits than its factorization.

21143730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8018.

The product of its (nonzero) digits is 504, while the sum is 21.

The square root of 21143730 is about 4598.2311816611. The cubic root of 21143730 is about 276.5204159208.

Adding to 21143730 its reverse (3734112), we get a palindrome (24877842).

The spelling of 21143730 in words is "twenty-one million, one hundred forty-three thousand, seven hundred thirty".