21740556 has 24 divisors (see below), whose sum is σ = 51589440. Its totient is φ = 7123792.

The previous prime is 21740549. The next prime is 21740557. The reversal of 21740556 is 65504712.

It is not an unprimeable number, because it can be changed into a prime (21740557) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14646 + ... + 16061.

It is an arithmetic number, because the mean of its divisors is an integer number (2149560).

Almost surely, 2^21740556 is an apocalyptic number.

It is an amenable number.

21740556 is an abundant number, since it is smaller than the sum of its proper divisors (29848884).

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

21740556 is a wasteful number, since it uses less digits than its factorization.

21740556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30773 (or 30771 counting only the distinct ones).

The product of its (nonzero) digits is 8400, while the sum is 30.

The square root of 21740556 is about 4662.6769135337. The cubic root of 21740556 is about 279.0981014455.

The spelling of 21740556 in words is "twenty-one million, seven hundred forty thousand, five hundred fifty-six".