1991154534 has 12 divisors (see below), whose sum is σ = 3982527684. Its totient is φ = 663681744.

The previous prime is 1991154523. The next prime is 1991154589. The reversal of 1991154534 is 4354511991.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 100194 + ... + 118410.

It is an arithmetic number, because the mean of its divisors is an integer number (331877307).

Almost surely, 2^1991154534 is an apocalyptic number.

1991154534 is an abundant number, since it is smaller than the sum of its proper divisors (1991373150).

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

1991154534 is an frugal number, since it uses more digits than its factorization.

1991154534 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36439 (or 18222 counting only the distinct ones).

The product of its digits is 97200, while the sum is 42.

The square root of 1991154534 is about 44622.3546442812. The cubic root of 1991154534 is about 1258.0608733707.

The spelling of 1991154534 in words is "one billion, nine hundred ninety-one million, one hundred fifty-four thousand, five hundred thirty-four".