2157221 has 4 divisors (see below), whose sum is σ = 2353344. Its totient is φ = 1961100.

The previous prime is 2157209. The next prime is 2157229. The reversal of 2157221 is 1227512.

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 not a de Polignac number, because 2157221 - 2⁶ = 2157157 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2157193 and 2157202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2157229) 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, 98045 + ... + 98066.

It is an arithmetic number, because the mean of its divisors is an integer number (588336).

2^2157221 is an apocalyptic number.

It is an amenable number.

2157221 is a deficient number, since it is larger than the sum of its proper divisors (196123).

2157221 is a wasteful number, since it uses less digits than its factorization.

2157221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 196122.

The product of its digits is 280, while the sum is 20.

The square root of 2157221 is about 1468.7481063818. The cubic root of 2157221 is about 129.2106208141.

The spelling of 2157221 in words is "two million, one hundred fifty-seven thousand, two hundred twenty-one".