1820521 has 2 divisors, whose sum is σ = 1820522. Its totient is φ = 1820520.

The previous prime is 1820509. The next prime is 1820527. The reversal of 1820521 is 1250281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1590121 + 230400 = 1261^2 + 480^2 .

It is an emirp because it is prime and its reverse (1250281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1820521 - 2⁹ = 1820009 is a prime.

It is a super-2 number, since 2×1820521² = 6628593422882, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1820527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 910260 + 910261.

It is an arithmetic number, because the mean of its divisors is an integer number (910261).

2^1820521 is an apocalyptic number.

It is an amenable number.

1820521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1820521 is an equidigital number, since it uses as much as digits as its factorization.

1820521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 160, while the sum is 19.

The square root of 1820521 is about 1349.2668379531. The cubic root of 1820521 is about 122.1045641212.

The spelling of 1820521 in words is "one million, eight hundred twenty thousand, five hundred twenty-one".