4156021 has 4 divisors (see below), whose sum is σ = 4174092. Its totient is φ = 4137952.

The previous prime is 4156001. The next prime is 4156037. The reversal of 4156021 is 1206514.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1206514 = 2 ⋅603257.

It can be written as a sum of positive squares in 2 ways, for example, as 2235025 + 1920996 = 1495^2 + 1386^2 .

It is a cyclic number.

It is not a de Polignac number, because 4156021 - 2⁵ = 4155989 is a prime.

It is a super-5 number, since 5×4156021⁵ (a number of 34 digits) contains 55555 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 4156021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4156001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8686 + ... + 9151.

It is an arithmetic number, because the mean of its divisors is an integer number (1043523).

Almost surely, 2^4156021 is an apocalyptic number.

It is an amenable number.

4156021 is a deficient number, since it is larger than the sum of its proper divisors (18071).

4156021 is a wasteful number, since it uses less digits than its factorization.

4156021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18070.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 4156021 is about 2038.6321394504. The cubic root of 4156021 is about 160.7777368458. Note that the first 4 decimals are identical.

It can be divided in two parts, 4 and 156021, that added together give a square (156025 = 395²).

The spelling of 4156021 in words is "four million, one hundred fifty-six thousand, twenty-one".