56721 has 16 divisors (see below), whose sum is σ = 89984. Its totient is φ = 31104.
The previous prime is 56713. The next prime is 56731. The reversal of 56721 is 12765.
It is not a de Polignac number, because 56721 - 23 = 56713 is a prime.
It is a Harshad number since it is a multiple of its sum of digits (21).
It is an alternating number because its digits alternate between odd and even.
56721 is a lucky number.
It is a nialpdrome in base 16.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (56701) 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, 741 + ... + 813.
It is an arithmetic number, because the mean of its divisors is an integer number (5624).
256721 is an apocalyptic number.
It is an amenable number.
56721 is a deficient number, since it is larger than the sum of its proper divisors (33263).
56721 is a wasteful number, since it uses less digits than its factorization.
56721 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 120.
The product of its digits is 420, while the sum is 21.
The square root of 56721 is about 238.1617097688. The cubic root of 56721 is about 38.4221172500.
56721 divided by its sum of digits (21) gives a triangular number (2701 = T73).
Subtracting from 56721 its reverse (12765), we obtain a triangular number (43956 = T296).
It can be divided in two parts, 56 and 721, that added together give a palindrome (777).
The spelling of 56721 in words is "fifty-six thousand, seven hundred twenty-one".
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