1331226661 has 4 divisors (see below), whose sum is σ = 1331316000. Its totient is φ = 1331137324.

The previous prime is 1331226629. The next prime is 1331226703. The reversal of 1331226661 is 1666221331.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1666221331 = 127 ⋅13119853.

It is a cyclic number.

It is not a de Polignac number, because 1331226661 - 2⁵ = 1331226629 is a prime.

It is a super-3 number, since 3×1331226661³ (a number of 28 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1331220661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16321 + ... + 54118.

It is an arithmetic number, because the mean of its divisors is an integer number (332829000).

Almost surely, 2^1331226661 is an apocalyptic number.

It is an amenable number.

1331226661 is a deficient number, since it is larger than the sum of its proper divisors (89339).

1331226661 is an equidigital number, since it uses as much as digits as its factorization.

1331226661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89338.

The product of its digits is 7776, while the sum is 31.

The square root of 1331226661 is about 36485.9789645283. The cubic root of 1331226661 is about 1100.0624375027.

Adding to 1331226661 its reverse (1666221331), we get a palindrome (2997447992).

The spelling of 1331226661 in words is "one billion, three hundred thirty-one million, two hundred twenty-six thousand, six hundred sixty-one".