3928821 has 16 divisors (see below), whose sum is σ = 5691840. Its totient is φ = 2396160.

The previous prime is 3928817. The next prime is 3928823. The reversal of 3928821 is 1288293.

3928821 = 104² + 105² + ... + 234².

It is not a de Polignac number, because 3928821 - 2² = 3928817 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3928823) 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, 4725 + ... + 5493.

It is an arithmetic number, because the mean of its divisors is an integer number (355740).

Almost surely, 2^3928821 is an apocalyptic number.

It is an amenable number.

3928821 is a deficient number, since it is larger than the sum of its proper divisors (1763019).

3928821 is a wasteful number, since it uses less digits than its factorization.

3928821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 916.

The product of its digits is 6912, while the sum is 33.

The square root of 3928821 is about 1982.1253744403. The cubic root of 3928821 is about 157.7928840959.

The spelling of 3928821 in words is "three million, nine hundred twenty-eight thousand, eight hundred twenty-one".