21015930 has 32 divisors (see below), whose sum is σ = 54319104. Its totient is φ = 5173056.

The previous prime is 21015913. The next prime is 21015941. The reversal of 21015930 is 3951012.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21015897 and 21015906.

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, 26554 + ... + 27333.

It is an arithmetic number, because the mean of its divisors is an integer number (1697472).

Almost surely, 2^21015930 is an apocalyptic number.

21015930 is an abundant number, since it is smaller than the sum of its proper divisors (33303174).

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

21015930 is a wasteful number, since it uses less digits than its factorization.

21015930 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53910.

The product of its (nonzero) digits is 270, while the sum is 21.

The square root of 21015930 is about 4584.3134709572. The cubic root of 21015930 is about 275.9621613743.

Adding to 21015930 its reverse (3951012), we get a palindrome (24966942).

It can be divided in two parts, 21015 and 930, that added together give a triangular number (21945 = T₂₀₉).

The spelling of 21015930 in words is "twenty-one million, fifteen thousand, nine hundred thirty".