3942821 has 4 divisors (see below), whose sum is σ = 4114272. Its totient is φ = 3771372.

The previous prime is 3942781. The next prime is 3942839. The reversal of 3942821 is 1282493.

3942821 = T₅₇₄ + T₅₇₅ + ... + T₅₉₆.

3942821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3942821 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3942871) 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, 85691 + ... + 85736.

It is an arithmetic number, because the mean of its divisors is an integer number (1028568).

Almost surely, 2^3942821 is an apocalyptic number.

It is an amenable number.

3942821 is a deficient number, since it is larger than the sum of its proper divisors (171451).

3942821 is a wasteful number, since it uses less digits than its factorization.

3942821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171450.

The product of its digits is 3456, while the sum is 29.

The square root of 3942821 is about 1985.6537966121. The cubic root of 3942821 is about 157.9800888224.

The spelling of 3942821 in words is "three million, nine hundred forty-two thousand, eight hundred twenty-one".