21256554 has 96 divisors (see below), whose sum is σ = 52093440. Its totient is φ = 5749920.

The previous prime is 21256541. The next prime is 21256559. The reversal of 21256554 is 45565212.

Its product of digits (12000) is a multiple of the sum of its prime divisors (125).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21256559) 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 47 ways as a sum of consecutive naturals, for example, 317229 + ... + 317295.

It is an arithmetic number, because the mean of its divisors is an integer number (542640).

Almost surely, 2^21256554 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21256554, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26046720).

21256554 is an abundant number, since it is smaller than the sum of its proper divisors (30836886).

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

21256554 is a wasteful number, since it uses less digits than its factorization.

21256554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136 (or 125 counting only the distinct ones).

The product of its digits is 12000, while the sum is 30.

The square root of 21256554 is about 4610.4830549521. The cubic root of 21256554 is about 277.0113859265.

The spelling of 21256554 in words is "twenty-one million, two hundred fifty-six thousand, five hundred fifty-four".