21151256 has 64 divisors (see below), whose sum is σ = 48422400.
Its totient is φ = 8460288.
The previous prime is 21151253. The next prime is 21151259. The reversal of 21151256 is 65215112.
It is a happy number.
It is an interprime number because it is at equal distance from previous prime (21151253) and next prime (21151259).
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (21151253) by changing a digit.
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 15 ways as a sum of consecutive naturals, for example, 109496 + ... + 109688.
It is an arithmetic number, because the mean of its divisors is an integer number (756600).
Almost surely, 221151256 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 21151256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24211200).
21151256 is an abundant number, since it is smaller than the sum of its proper divisors (27271144).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
21151256 is a wasteful number, since it uses less digits than its factorization.
21151256 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 328 (or 324 counting only the distinct ones).
The product of its digits is 600, while the sum is 23.
The square root of 21151256 is about 4599.0494670095.
The cubic root of 21151256 is about 276.5532206937.
Adding to 21151256 its reverse (65215112), we get a palindrome (86366368).
The spelling of 21151256 in words is "twenty-one million, one hundred fifty-one thousand, two hundred fifty-six".