21713556 has 48 divisors (see below), whose sum is σ = 54057024. Its totient is φ = 6759936.

The previous prime is 21713521. The next prime is 21713567. The reversal of 21713556 is 65531712.

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 15 ways as a sum of consecutive naturals, for example, 32926 + ... + 33578.

It is an arithmetic number, because the mean of its divisors is an integer number (1126188).

Almost surely, 2^21713556 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 21713556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27028512).

21713556 is an abundant number, since it is smaller than the sum of its proper divisors (32343468).

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

21713556 is a wasteful number, since it uses less digits than its factorization.

21713556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 840 (or 838 counting only the distinct ones).

The product of its digits is 6300, while the sum is 30.

The square root of 21713556 is about 4659.7806815343. The cubic root of 21713556 is about 278.9825145450.

The spelling of 21713556 in words is "twenty-one million, seven hundred thirteen thousand, five hundred fifty-six".