4006821 has 24 divisors (see below), whose sum is σ = 6617280. Its totient is φ = 2111616.

The previous prime is 4006811. The next prime is 4006823. The reversal of 4006821 is 1286004.

It is not a de Polignac number, because 4006821 - 2⁵ = 4006789 is a prime.

It is a super-2 number, since 2×4006821² = 32109229052082, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4006823) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2985 + ... + 4113.

It is an arithmetic number, because the mean of its divisors is an integer number (275720).

Almost surely, 2^4006821 is an apocalyptic number.

It is an amenable number.

4006821 is a deficient number, since it is larger than the sum of its proper divisors (2610459).

4006821 is a wasteful number, since it uses less digits than its factorization.

4006821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1165 (or 1152 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 4006821 is about 2001.7045236498. The cubic root of 4006821 is about 158.8302844783.

The spelling of 4006821 in words is "four million, six thousand, eight hundred twenty-one".