21140730 has 128 divisors (see below), whose sum is σ = 64108800. Its totient is φ = 4914432.

The previous prime is 21140719. The next prime is 21140731. The reversal of 21140730 is 3704112.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21140731) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 66532 + ... + 66848.

It is an arithmetic number, because the mean of its divisors is an integer number (500850).

Almost surely, 2^21140730 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21140730, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32054400).

21140730 is an abundant number, since it is smaller than the sum of its proper divisors (42968070).

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

21140730 is a wasteful number, since it uses less digits than its factorization.

21140730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 365 (or 359 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 21140730 is about 4597.9049576954. The cubic root of 21140730 is about 276.5073371738.

Adding to 21140730 its reverse (3704112), we get a palindrome (24844842).

The spelling of 21140730 in words is "twenty-one million, one hundred forty thousand, seven hundred thirty".