1821411661 has 2 divisors, whose sum is σ = 1821411662. Its totient is φ = 1821411660.

The previous prime is 1821411623. The next prime is 1821411689. The reversal of 1821411661 is 1661141281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1821155625 + 256036 = 42675^2 + 506^2 .

It is a cyclic number.

It is not a de Polignac number, because 1821411661 - 2⁷ = 1821411533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1821411601) 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, 910705830 + 910705831.

It is an arithmetic number, because the mean of its divisors is an integer number (910705831).

Almost surely, 2^1821411661 is an apocalyptic number.

It is an amenable number.

1821411661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1821411661 is an equidigital number, since it uses as much as digits as its factorization.

1821411661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2304, while the sum is 31.

The square root of 1821411661 is about 42677.9997305403. Note that the first 3 decimals coincide. The cubic root of 1821411661 is about 1221.2447344799.

The spelling of 1821411661 in words is "one billion, eight hundred twenty-one million, four hundred eleven thousand, six hundred sixty-one".