21520856 has 16 divisors (see below), whose sum is σ = 46116240. Its totient is φ = 9223200.

The previous prime is 21520853. The next prime is 21520867. The reversal of 21520856 is 65802512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21520853) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 192095 + ... + 192206.

It is an arithmetic number, because the mean of its divisors is an integer number (2882265).

Almost surely, 2^21520856 is an apocalyptic number.

It is an amenable number.

21520856 is an abundant number, since it is smaller than the sum of its proper divisors (24595384).

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

21520856 is a wasteful number, since it uses less digits than its factorization.

21520856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 384314 (or 384310 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 29.

The square root of 21520856 is about 4639.0576629311. The cubic root of 21520856 is about 278.1547712271.

The spelling of 21520856 in words is "twenty-one million, five hundred twenty thousand, eight hundred fifty-six".