21191256 has 48 divisors (see below), whose sum is σ = 58055400. Its totient is φ = 6982272.

The previous prime is 21191239. The next prime is 21191263. The reversal of 21191256 is 65219112.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4755 + ... + 8061.

Almost surely, 2^21191256 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21191256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29027700).

21191256 is an abundant number, since it is smaller than the sum of its proper divisors (36864144).

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

21191256 is a wasteful number, since it uses less digits than its factorization.

21191256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3408 (or 3401 counting only the distinct ones).

The product of its digits is 1080, while the sum is 27.

The square root of 21191256 is about 4603.3961376358. The cubic root of 21191256 is about 276.7274445916.

It can be divided in two parts, 2119 and 1256, that added together give a cube (3375 = 15³).

The spelling of 21191256 in words is "twenty-one million, one hundred ninety-one thousand, two hundred fifty-six".