1331229991 has 64 divisors (see below), whose sum is σ = 1756339200. Its totient is φ = 1001669760.

The previous prime is 1331229941. The next prime is 1331229997. The reversal of 1331229991 is 1999221331.

It is not a de Polignac number, because 1331229991 - 2¹³ = 1331221799 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1331229997) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 10161996 + ... + 10162126.

It is an arithmetic number, because the mean of its divisors is an integer number (27442800).

Almost surely, 2^1331229991 is an apocalyptic number.

1331229991 is a deficient number, since it is larger than the sum of its proper divisors (425109209).

1331229991 is a wasteful number, since it uses less digits than its factorization.

1331229991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 261 (or 247 counting only the distinct ones).

The product of its digits is 26244, while the sum is 40.

The square root of 1331229991 is about 36486.0245984678. The cubic root of 1331229991 is about 1100.0633547532.

The spelling of 1331229991 in words is "one billion, three hundred thirty-one million, two hundred twenty-nine thousand, nine hundred ninety-one".