21102730 has 64 divisors (see below), whose sum is σ = 45619200. Its totient is φ = 6937920.

The previous prime is 21102709. The next prime is 21102737. The reversal of 21102730 is 3720112.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21102737) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 47851 + ... + 48289.

It is an arithmetic number, because the mean of its divisors is an integer number (712800).

Almost surely, 2^21102730 is an apocalyptic number.

21102730 is an abundant number, since it is smaller than the sum of its proper divisors (24516470).

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

21102730 is a wasteful number, since it uses less digits than its factorization.

21102730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 499.

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 21102730 is about 4593.7707822659. The cubic root of 21102730 is about 276.3415658461.

Adding to 21102730 its reverse (3720112), we get a palindrome (24822842).

The spelling of 21102730 in words is "twenty-one million, one hundred two thousand, seven hundred thirty".