21471856 has 40 divisors (see below), whose sum is σ = 48568320. Its totient is φ = 9004224.

The previous prime is 21471839. The next prime is 21471883. The reversal of 21471856 is 65817412.

It is a super-2 number, since 2×21471856² = 922081200169472, which contains 22 as substring.

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 7 ways as a sum of consecutive naturals, for example, 3225 + ... + 7303.

It is an arithmetic number, because the mean of its divisors is an integer number (1214208).

Almost surely, 2^21471856 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 21471856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24284160).

21471856 is an abundant number, since it is smaller than the sum of its proper divisors (27096464).

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

21471856 is a wasteful number, since it uses less digits than its factorization.

21471856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4141 (or 4135 counting only the distinct ones).

The product of its digits is 13440, while the sum is 34.

The square root of 21471856 is about 4633.7734083574. The cubic root of 21471856 is about 277.9435042106.

The spelling of 21471856 in words is "twenty-one million, four hundred seventy-one thousand, eight hundred fifty-six".