83011991 has 16 divisors (see below), whose sum is σ = 88646400. Its totient is φ = 77571648.

The previous prime is 83011987. The next prime is 83012021. The reversal of 83011991 is 19911038.

It is a cyclic number.

It is not a de Polignac number, because 83011991 - 2² = 83011987 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (83011961) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 218840 + ... + 219218.

It is an arithmetic number, because the mean of its divisors is an integer number (5540400).

Almost surely, 2^83011991 is an apocalyptic number.

83011991 is a deficient number, since it is larger than the sum of its proper divisors (5634409).

83011991 is a wasteful number, since it uses less digits than its factorization.

83011991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 598.

The product of its (nonzero) digits is 1944, while the sum is 32.

The square root of 83011991 is about 9111.0916469982. The cubic root of 83011991 is about 436.2280723948.

It can be divided in two parts, 830 and 11991, that added together give a palindrome (12821).

The spelling of 83011991 in words is "eighty-three million, eleven thousand, nine hundred ninety-one".