2179921 has 2 divisors, whose sum is σ = 2179922. Its totient is φ = 2179920.

The previous prime is 2179909. The next prime is 2179939. The reversal of 2179921 is 1299712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1661521 + 518400 = 1289^2 + 720^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2179921 is a prime.

It is a Chen prime.

It is an Ulam number.

It is not a weakly prime, because it can be changed into another prime (2179981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1089960 + 1089961.

It is an arithmetic number, because the mean of its divisors is an integer number (1089961).

2^2179921 is an apocalyptic number.

It is an amenable number.

2179921 is a deficient number, since it is larger than the sum of its proper divisors (1).

2179921 is an equidigital number, since it uses as much as digits as its factorization.

2179921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2268, while the sum is 31.

The square root of 2179921 is about 1476.4555530052. The cubic root of 2179921 is about 129.6622594029.

The spelling of 2179921 in words is "two million, one hundred seventy-nine thousand, nine hundred twenty-one".