2578721 has 2 divisors, whose sum is σ = 2578722. Its totient is φ = 2578720.

The previous prime is 2578717. The next prime is 2578729. The reversal of 2578721 is 1278752.

2578721 = 1135² + 1136².

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1290496 + 1288225 = 1136^2 + 1135^2 .

It is a cyclic number.

It is not a de Polignac number, because 2578721 - 2² = 2578717 is a prime.

It is not a weakly prime, because it can be changed into another prime (2578729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1289360 + 1289361.

It is an arithmetic number, because the mean of its divisors is an integer number (1289361).

2^2578721 is an apocalyptic number.

2578721 is the 1136-th centered square number.

It is an amenable number.

2578721 is a deficient number, since it is larger than the sum of its proper divisors (1).

2578721 is an equidigital number, since it uses as much as digits as its factorization.

2578721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7840, while the sum is 32.

The square root of 2578721 is about 1605.8396557565. The cubic root of 2578721 is about 137.1307292826.

The spelling of 2578721 in words is "two million, five hundred seventy-eight thousand, seven hundred twenty-one".