1221799681 has 8 divisors (see below), whose sum is σ = 1267761320. Its totient is φ = 1176519168.

The previous prime is 1221799679. The next prime is 1221799729. The reversal of 1221799681 is 1869971221.

It can be written as a sum of positive squares in 4 ways, for example, as 626000400 + 595799281 = 25020^2 + 24409^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221799681 - 2¹ = 1221799679 is a prime.

It is a super-2 number, since 2×1221799681² = 2985588920983403522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221799661) 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 in 7 ways as a sum of consecutive naturals, for example, 166626 + ... + 173803.

It is an arithmetic number, because the mean of its divisors is an integer number (158470165).

Almost surely, 2^1221799681 is an apocalyptic number.

It is an amenable number.

1221799681 is a deficient number, since it is larger than the sum of its proper divisors (45961639).

1221799681 is an equidigital number, since it uses as much as digits as its factorization.

1221799681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 340563.

The product of its digits is 108864, while the sum is 46.

The square root of 1221799681 is about 34954.2512578942. The cubic root of 1221799681 is about 1069.0548852995.

The spelling of 1221799681 in words is "one billion, two hundred twenty-one million, seven hundred ninety-nine thousand, six hundred eighty-one".