2157321 has 8 divisors (see below), whose sum is σ = 2969344. Its totient is φ = 1391760.

The previous prime is 2157319. The next prime is 2157329. The reversal of 2157321 is 1237512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 2157321 - 2¹ = 2157319 is a prime.

It is a d-powerful number, because it can be written as 2¹¹ + 1 + 5⁹ + 7⁵ + 3¹¹ + 2¹³ + 1 .

It is a Duffinian number.

It is a Curzon number.

2157321 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (2157329) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11506 + ... + 11691.

It is an arithmetic number, because the mean of its divisors is an integer number (371168).

2^2157321 is an apocalyptic number.

It is an amenable number.

2157321 is a deficient number, since it is larger than the sum of its proper divisors (812023).

2157321 is a wasteful number, since it uses less digits than its factorization.

2157321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23231.

The product of its digits is 420, while the sum is 21.

The square root of 2157321 is about 1468.7821485843. The cubic root of 2157321 is about 129.2126173430.

The spelling of 2157321 in words is "two million, one hundred fifty-seven thousand, three hundred twenty-one".