2151221 has 2 divisors, whose sum is σ = 2151222. Its totient is φ = 2151220.

The previous prime is 2151211. The next prime is 2151241. The reversal of 2151221 is 1221512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2002225 + 148996 = 1415^2 + 386^2 .

It is a cyclic number.

It is not a de Polignac number, because 2151221 - 2⁶ = 2151157 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 2151196 and 2151205.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2151211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1075610 + 1075611.

It is an arithmetic number, because the mean of its divisors is an integer number (1075611).

2^2151221 is an apocalyptic number.

It is an amenable number.

2151221 is a deficient number, since it is larger than the sum of its proper divisors (1).

2151221 is an equidigital number, since it uses as much as digits as its factorization.

2151221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40, while the sum is 14.

The square root of 2151221 is about 1466.7041283095. The cubic root of 2151221 is about 129.0907159922.

Adding to 2151221 its reverse (1221512), we get a palindrome (3372733).

The spelling of 2151221 in words is "two million, one hundred fifty-one thousand, two hundred twenty-one".