91881261 has 6 divisors (see below), whose sum is σ = 132717390. Its totient is φ = 61254168.

The previous prime is 91881259. The next prime is 91881263. The reversal of 91881261 is 16218819.

It is an interprime number because it is at equal distance from previous prime (91881259) and next prime (91881263).

It can be written as a sum of positive squares in only one way, i.e., 80892036 + 10989225 = 8994^2 + 3315^2 .

It is not a de Polignac number, because 91881261 - 2¹ = 91881259 is a prime.

It is a super-2 number, since 2×91881261² = 16884332245900242, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91881263) by changing a digit.

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, 5104506 + ... + 5104523.

It is an arithmetic number, because the mean of its divisors is an integer number (22119565).

Almost surely, 2^91881261 is an apocalyptic number.

It is an amenable number.

91881261 is a deficient number, since it is larger than the sum of its proper divisors (40836129).

91881261 is a wasteful number, since it uses less digits than its factorization.

91881261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10209035 (or 10209032 counting only the distinct ones).

The product of its digits is 6912, while the sum is 36.

The square root of 91881261 is about 9585.4713499128. The cubic root of 91881261 is about 451.2414460617.

The spelling of 91881261 in words is "ninety-one million, eight hundred eighty-one thousand, two hundred sixty-one".