21017120 has 24 divisors (see below), whose sum is σ = 49653324. Its totient is φ = 8406784.

The previous prime is 21017111. The next prime is 21017137. The reversal of 21017120 is 2171012.

It can be written as a sum of positive squares in 2 ways, for example, as 20178064 + 839056 = 4492^2 + 916^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21017095 and 21017104.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65519 + ... + 65838.

Almost surely, 2^21017120 is an apocalyptic number.

21017120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21017120 is an abundant number, since it is smaller than the sum of its proper divisors (28636204).

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

21017120 is a wasteful number, since it uses less digits than its factorization.

21017120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131372 (or 131364 counting only the distinct ones).

The product of its (nonzero) digits is 28, while the sum is 14.

The square root of 21017120 is about 4584.4432595464. The cubic root of 21017120 is about 275.9673699435.

Adding to 21017120 its reverse (2171012), we get a palindrome (23188132).

The spelling of 21017120 in words is "twenty-one million, seventeen thousand, one hundred twenty".