4661221681 has 2 divisors, whose sum is σ = 4661221682. Its totient is φ = 4661221680.

The previous prime is 4661221679. The next prime is 4661221703. The reversal of 4661221681 is 1861221664.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3561702400 + 1099519281 = 59680^2 + 33159^2 .

It is a cyclic number.

It is not a de Polignac number, because 4661221681 - 2¹ = 4661221679 is a prime.

It is a super-2 number, since 2×4661221681² = 43453975118848931522, which contains 22 as substring.

Together with 4661221679, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 4661221681.

It is not a weakly prime, because it can be changed into another prime (4661224681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2330610840 + 2330610841.

It is an arithmetic number, because the mean of its divisors is an integer number (2330610841).

Almost surely, 2^4661221681 is an apocalyptic number.

It is an amenable number.

4661221681 is a deficient number, since it is larger than the sum of its proper divisors (1).

4661221681 is an equidigital number, since it uses as much as digits as its factorization.

4661221681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27648, while the sum is 37.

The square root of 4661221681 is about 68273.1402602810. The cubic root of 4661221681 is about 1670.4491221555.

The spelling of 4661221681 in words is "four billion, six hundred sixty-one million, two hundred twenty-one thousand, six hundred eighty-one".