91991412 has 18 divisors (see below), whose sum is σ = 232533938. Its totient is φ = 30663792.

The previous prime is 91991401. The next prime is 91991441. The reversal of 91991412 is 21419919.

It can be written as a sum of positive squares in only one way, i.e., 89189136 + 2802276 = 9444^2 + 1674^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 2555317 = 91991412 / (9 + 1 + 9 + 9 + 1 + 4 + 1 + 2).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1277623 + ... + 1277694.

Almost surely, 2^91991412 is an apocalyptic number.

It is an amenable number.

91991412 is an abundant number, since it is smaller than the sum of its proper divisors (140542526).

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

91991412 is a wasteful number, since it uses less digits than its factorization.

91991412 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2555327 (or 2555322 counting only the distinct ones).

The product of its digits is 5832, while the sum is 36.

The square root of 91991412 is about 9591.2153557305. The cubic root of 91991412 is about 451.4216962619.

The spelling of 91991412 in words is "ninety-one million, nine hundred ninety-one thousand, four hundred twelve".