40821 has 8 divisors (see below), whose sum is σ = 59424. Its totient is φ = 24720.

The previous prime is 40819. The next prime is 40823. The reversal of 40821 is 12804.

It is an interprime number because it is at equal distance from previous prime (40819) and next prime (40823).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 40821 - 2¹ = 40819 is a prime.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 40821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (40823) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 586 + ... + 651.

It is an arithmetic number, because the mean of its divisors is an integer number (7428).

2⁴⁰⁸²¹ is an apocalyptic number.

It is an amenable number.

40821 is a deficient number, since it is larger than the sum of its proper divisors (18603).

40821 is a wasteful number, since it uses less digits than its factorization.

40821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1251.

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 40821 is about 202.0420748260. The cubic root of 40821 is about 34.4319178252.

It can be divided in two parts, 40 and 821, that added together give a triangular number (861 = T₄₁).

The spelling of 40821 in words is "forty thousand, eight hundred twenty-one".