21275556 has 48 divisors (see below), whose sum is σ = 51565248. Its totient is φ = 6822400.

The previous prime is 21275543. The next prime is 21275557. The reversal of 21275556 is 65557212.

It is not an unprimeable number, because it can be changed into a prime (21275557) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 40576 + ... + 41096.

It is an arithmetic number, because the mean of its divisors is an integer number (1074276).

Almost surely, 2^21275556 is an apocalyptic number.

It is an amenable number.

21275556 is an abundant number, since it is smaller than the sum of its proper divisors (30289692).

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

21275556 is a wasteful number, since it uses less digits than its factorization.

21275556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 652 (or 650 counting only the distinct ones).

The product of its digits is 21000, while the sum is 33.

The square root of 21275556 is about 4612.5433331298. The cubic root of 21275556 is about 277.0939048309.

The spelling of 21275556 in words is "twenty-one million, two hundred seventy-five thousand, five hundred fifty-six".