40921 has 4 divisors (see below), whose sum is σ = 41344. Its totient is φ = 40500.
The previous prime is 40903. The next prime is 40927. The reversal of 40921 is 12904.
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.
It is a 4-Lehmer number, since φ(40921) divides (40921-1)4.
It is a cyclic number.
It is not a de Polignac number, because 40921 - 211 = 38873 is a prime.
It is a Duffinian number.
40921 is a lucky number.
It is a junction number, because it is equal to n+sod(n) for n = 40895 and 40904.
It is not an unprimeable number, because it can be changed into a prime (40927) 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 3 ways as a sum of consecutive naturals, for example, 16 + ... + 286.
It is an arithmetic number, because the mean of its divisors is an integer number (10336).
240921 is an apocalyptic number.
It is an amenable number.
40921 is a deficient number, since it is larger than the sum of its proper divisors (423).
40921 is a wasteful number, since it uses less digits than its factorization.
40921 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 422.
The product of its (nonzero) digits is 72, while the sum is 16.
The square root of 40921 is about 202.2893966574. The cubic root of 40921 is about 34.4600110777.
It can be divided in two parts, 40 and 921, that added together give a square (961 = 312).
The spelling of 40921 in words is "forty thousand, nine hundred twenty-one".
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