21171056 has 30 divisors (see below), whose sum is σ = 41980200. Its totient is φ = 10343008.

The previous prime is 21171049. The next prime is 21171089. The reversal of 21171056 is 65017112.

It is a super-2 number, since 2×21171056² = 896427224310272, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35045 + ... + 35643.

It is an arithmetic number, because the mean of its divisors is an integer number (1399340).

Almost surely, 2^21171056 is an apocalyptic number.

It is an amenable number.

21171056 is a deficient number, since it is larger than the sum of its proper divisors (20809144).

21171056 is an equidigital number, since it uses as much as digits as its factorization.

21171056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 701 (or 648 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 23.

The square root of 21171056 is about 4601.2015821957. The cubic root of 21171056 is about 276.6394889514.

Adding to 21171056 its reverse (65017112), we get a palindrome (86188168).

The spelling of 21171056 in words is "twenty-one million, one hundred seventy-one thousand, fifty-six".