1591991136 has 36 divisors (see below), whose sum is σ = 4527225612. Its totient is φ = 530663616.

The previous prime is 1591991131. The next prime is 1591991183. The reversal of 1591991136 is 6311991951.

It is a tau number, because it is divible by the number of its divisors (36).

It is a junction number, because it is equal to n+sod(n) for n = 1591991091 and 1591991100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1591991131) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2763586 + ... + 2764161.

It is an arithmetic number, because the mean of its divisors is an integer number (125756267).

Almost surely, 2^1591991136 is an apocalyptic number.

1591991136 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1591991136 is an abundant number, since it is smaller than the sum of its proper divisors (2935234476).

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

1591991136 is a wasteful number, since it uses less digits than its factorization.

1591991136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5527763 (or 5527752 counting only the distinct ones).

The product of its digits is 65610, while the sum is 45.

The square root of 1591991136 is about 39899.7636083223. The cubic root of 1591991136 is about 1167.6523250546.

The spelling of 1591991136 in words is "one billion, five hundred ninety-one million, nine hundred ninety-one thousand, one hundred thirty-six".