1231491771 has 12 divisors (see below), whose sum is σ = 1836203200. Its totient is φ = 794510640.

The previous prime is 1231491761. The next prime is 1231491797. The reversal of 1231491771 is 1771941321.

It is not a de Polignac number, because 1231491771 - 2⁵ = 1231491739 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1231491721) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2206696 + ... + 2207253.

Almost surely, 2^1231491771 is an apocalyptic number.

1231491771 is a deficient number, since it is larger than the sum of its proper divisors (604711429).

1231491771 is a wasteful number, since it uses less digits than its factorization.

1231491771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4413986 (or 4413983 counting only the distinct ones).

The product of its digits is 10584, while the sum is 36.

The square root of 1231491771 is about 35092.6170440450. The cubic root of 1231491771 is about 1071.8742505255.

The spelling of 1231491771 in words is "one billion, two hundred thirty-one million, four hundred ninety-one thousand, seven hundred seventy-one".