21500856 has 192 divisors, whose sum is σ = 70272000. Its totient is φ = 6065280.

The previous prime is 21500833. The next prime is 21500893. The reversal of 21500856 is 65800512.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 693561 + ... + 693591.

It is an arithmetic number, because the mean of its divisors is an integer number (366000).

Almost surely, 2^21500856 is an apocalyptic number.

21500856 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21500856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35136000).

21500856 is an abundant number, since it is smaller than the sum of its proper divisors (48771144).

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

21500856 is a wasteful number, since it uses less digits than its factorization.

21500856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91 (or 68 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

The square root of 21500856 is about 4636.9015516830. The cubic root of 21500856 is about 278.0685785646.

The spelling of 21500856 in words is "twenty-one million, five hundred thousand, eight hundred fifty-six".