1291531388 has 24 divisors (see below), whose sum is σ = 2600177664. Its totient is φ = 549846000.

The previous prime is 1291531379. The next prime is 1291531399. The reversal of 1291531388 is 8831351921.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 148508 + ... + 156963.

It is an arithmetic number, because the mean of its divisors is an integer number (108340736).

Almost surely, 2^1291531388 is an apocalyptic number.

It is an amenable number.

1291531388 is an abundant number, since it is smaller than the sum of its proper divisors (1308646276).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1291531388 is a wasteful number, since it uses less digits than its factorization.

1291531388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305633 (or 305631 counting only the distinct ones).

The product of its digits is 51840, while the sum is 41.

The square root of 1291531388 is about 35937.8823527486. The cubic root of 1291531388 is about 1089.0178252351.

The spelling of 1291531388 in words is "one billion, two hundred ninety-one million, five hundred thirty-one thousand, three hundred eighty-eight".