2781521 has 2 divisors, whose sum is σ = 2781522. Its totient is φ = 2781520.

The previous prime is 2781503. The next prime is 2781577. The reversal of 2781521 is 1251872.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2755600 + 25921 = 1660^2 + 161^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2781521 is a prime.

It is not a weakly prime, because it can be changed into another prime (2781221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1390760 + 1390761.

It is an arithmetic number, because the mean of its divisors is an integer number (1390761).

2^2781521 is an apocalyptic number.

It is an amenable number.

2781521 is a deficient number, since it is larger than the sum of its proper divisors (1).

2781521 is an equidigital number, since it uses as much as digits as its factorization.

2781521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1120, while the sum is 26.

The square root of 2781521 is about 1667.7892552718. The cubic root of 2781521 is about 140.6352256597.

The spelling of 2781521 in words is "two million, seven hundred eighty-one thousand, five hundred twenty-one".